There were quite a few people at the car pickup. The lady assisting us saw we were Chinese and tried to upsell us. She said we could upgrade from our booked Peugeot 308 to the latest 2018 Alfa Romeo Q4 SUV for just an additional 20 euros per day. Considering our luggage and vehicle condition, we agreed to the upgrade. She told us we'd need to pay a total of about 260 euros extra at drop-off (I signed the document but forgot the exact amount). We confirmed multiple times if the total additional cost would only be 260 euros, and she reassured us. We also repeatedly mentioned that we had already purchased insurance and didn't need any additional coverage, but she concealed other significant fees from us and didn't provide a paper contract, only an email. This email was sent to the car rental platform. When we returned the car, we found out there was an extra 600 euros to pay. The return agent tried to force us to sign and agree to pay. We proactively contacted the car rental platform, and they mentioned our emails were flagged, indicating an issue, though we had not contacted them previously. Our experience with Avis was so poor that we wouldn't even give them a single star. We thought being a large company, they would provide better service, but even large companies deceive Chinese customers.