I spent two weeks responding to every return reason twice
I sell hiking gear and outdoor clothing on Allegro—waterproof jackets, trekking poles, thermal layers, head torches. About 60% of my revenue comes from Poland, the rest from Czechia and Slovakia through Allegro's cross-border programme. In January I had 95 return requests across all three markets. Polish consumer law gives buyers 14 days to return anything without a reason, and Allegro's own policy stretches that to 30 days for some categories, so returns are just part of the business. But every return email matters. Write something too stiff and the buyer leaves a one-star review. Write something too casual and they escalate to Allegro support, which flags your account.
I'd been using Claude Sonnet 4.5 for all my return emails since November. It writes polite, clear responses and handles Polish, Czech, and Slovak without mixing up formal pronouns. But I kept seeing people say Gemini Pro was better for customer service, so I decided to test both models on the same 95 returns. I wrote every response twice—once with Claude, once with Gemini—and tracked which one needed fewer edits, which one the customer replied to positively, and which one led to an escalation or a bad review.
This isn't a scientific study. I didn't control for time of day or customer mood, and some return reasons only came up three or four times. But after two weeks I had clear preferences for each return scenario, and I'm sharing them here because most EU marketplace sellers are handling this work manually and wondering whether Claude vs Gemini makes a practical difference for Allegro returns and marketplace customer service.
Late delivery: Claude wins by staying factual
Late delivery was the most common reason—32 returns out of 95. The package arrived after the customer left for a ski trip, or it sat in a Poczta Polska depot for nine days, or DPD marked it delivered but the customer never saw it. The buyer wants a refund and an acknowledgement that something went wrong, but they don't want a long apology that sounds like you're admitting liability.
Claude Sonnet 4.5 writes short, factual responses that acknowledge the delay without over-apologising. It references the tracking number, confirms the refund timeline, and stops. Gemini Pro adds an extra paragraph explaining what might have caused the delay—customs, weather, carrier backlogs—which sounds helpful but actually irritates people. They don't care why it was late; they care that you're processing the refund.
I used this prompt for both models: "Write a return approval email for a late delivery. Customer ordered a waterproof jacket on 8 January, expected delivery 12 January, package arrived 19 January. Customer wants a full refund. Tracking number: PL45829DPD. Respond in Polish, formal tone, GDPR-compliant—don't store unnecessary details."
Claude's response was 68 words. Gemini's was 114. The extra words didn't add value, and two customers replied asking if the delay meant there was a problem with future orders. Claude's version got zero follow-up questions.
Wrong size or colour: Gemini handles the exchange flow better
Wrong size was the second most common reason—19 returns. The customer ordered a men's large jacket but needed an XL, or they ordered navy and wanted black. Half of them wanted an exchange, half wanted a refund. Allegro doesn't have a built-in exchange system, so you have to explain the process: refund the original order, place a new order for the correct item, and we'll prioritise shipping.
Gemini Pro writes clearer exchange instructions than Claude. It breaks the steps into a numbered list, confirms stock availability for the new size, and includes a line about how long the refund will take to appear in their bank account (3–5 business days via SEPA). Claude writes the same information but buries it in a paragraph, and three customers replied asking me to repeat the steps.
I tested both models on a return where the customer ordered a size M thermal base layer but needed L. Gemini's response included a sentence I hadn't thought to add: "If you'd like to place a new order now, I can send you a €5 discount code to cover any price difference." That's not something I'd asked for in the prompt, but it's smart—it turns a return into a repeat purchase. I added that line to my standard exchange template.
Damaged goods: Claude is more careful with GDPR language
Damaged goods accounted for 14 returns—torn packaging, a broken buckle on a rucksack, a jacket with a stain on the sleeve. These need a different tone because the customer is frustrated and you need photos to verify the damage before approving the return. You also need to be careful about what you ask for. Under GDPR you can't request photos that show the customer's face, home address on a delivery label, or other people in the background. You need to say "please send a photo of the damaged item only" and explain why you're asking.
Claude Sonnet 4.5 writes GDPR-compliant emails that explain the photo request clearly: "To process your return quickly, please send a photo showing the damaged area of the jacket. You don't need to include any packaging labels or personal information—just the item itself." Gemini Pro writes something similar but doesn't always include the "you don't need to include" part, which led one customer to send me a photo with their full address visible on the return label in the background. I had to delete it immediately and ask again.
Both models approved the return politely once I confirmed the damage, but Claude's upfront clarity about what not to send saved me from a potential GDPR headache.
Buyer's remorse: Gemini is warmer without sounding desperate
Buyer's remorse—"I changed my mind", "I found a cheaper option", "I don't need it anymore"—was 18 returns. These are straightforward under EU distance selling rules: approve the return, confirm the refund, done. But the tone matters because these customers might buy again if you don't make them feel guilty.
Gemini Pro writes warmer, more conversational responses for buyer's remorse returns. It includes a line like "No problem at all—thanks for letting us know" or "We hope you'll find what you're looking for." Claude's responses are polite but neutral, and they feel slightly colder. Two customers who returned items due to buyer's remorse placed new orders within a week after receiving Gemini's response. That's not proof of causation, but it's worth noting.
I used the same prompt for both: "Approve a return for buyer's remorse. Customer ordered trekking poles, changed their mind, wants a refund. Respond in Polish, friendly but professional."
Gemini's version felt like a person. Claude's felt like a policy document. For this return reason, I'll keep using Gemini.
Customs issues for cross-border orders: Claude explains duties more clearly
Twelve returns came from customers in Czechia and Slovakia who were surprised by customs fees or VAT charges. Allegro's cross-border programme is supposed to handle this, but occasionally a package gets flagged and the buyer has to pay €8–€15 in duties. They're annoyed, they want a refund, and they want to know why it happened.
Claude Sonnet 4.5 explains customs rules more clearly than Gemini. It writes a short paragraph confirming the refund, then adds a sentence explaining that customs fees are set by the destination country and aren't part of the product price. It doesn't apologise for something I didn't control, and it doesn't promise it won't happen again (because I can't promise that). Gemini Pro adds an apology and a line about "working to improve our shipping process," which sounds like I did something wrong.
One customer in Brno replied to Claude's email saying "thanks for explaining—I didn't realise that's how it works." That's the response I want: informed, not angry.
The model I use depends on the return reason now
I still use Claude Sonnet 4.5 for most AI for e-commerce tasks—product descriptions, Allegro listing updates, VAT calculations. But after testing both models on 95 real returns, I've split my workflow by return reason. Late delivery, damaged goods, and customs issues go to Claude. Wrong size exchanges and buyer's remorse go to Gemini. I keep both models open in Kryotta's workspace and paste the return details into whichever one fits.
This adds about four seconds per email compared to using one model for everything, but it's cut my average edits per response from three to one, and I've had zero escalations to Allegro support since I started splitting the work. The time I save on edits and follow-up questions is worth the extra tab.
Questions people ask
Can I use the same prompt for Claude and Gemini, or do they need different instructions?
I use the same prompt for both. The differences in output come from how each model interprets tone and structure, not from needing special prompt formats. Both handle "respond in Polish, formal tone, GDPR-compliant" without extra explanation.
Does Gemini Pro cost more than Claude Sonnet 4.5 for return emails?
On Kryotta they're both included in the standard plan, so cost per email is the same. If you're using API access directly, Gemini Pro is slightly cheaper per token, but the difference is under €0.02 per email—not enough to matter.
What if the customer replies in Czech or Slovak instead of Polish?
Both models handle Czech and Slovak well. I specify the language in the prompt based on which country the order shipped to. If a customer replies in a different language, I paste their message into the model and it switches automatically.
Should I approve every return immediately or ask questions first?
Under EU consumer law you have to approve returns within 14 days of purchase unless the item is personalised or perishable. I approve immediately for late delivery and buyer's remorse. For damaged goods I ask for a photo first, and both Claude and Gemini write that request clearly.
If you're handling Allegro, Bol, or Zalando returns manually and you're not sure which model to try first, start with Claude for the factual stuff—late delivery, damaged goods, customs—and Gemini for the tone-sensitive stuff—exchanges and buyer's remorse. You can test both in one workspace at Kryotta and see which one cuts your editing time.
