There were many people, so I waited for a while. They tried to sell insurance, but I had already bought full coverage, so I didn't buy it. When I returned the car, they gave me a slip which I thought was for highway fees, but after a closer look, it was for fuel. I had clearly returned the car with a full tank. Luckily, I noticed in time and went back to the counter to cancel it. They canceled it without checking, which felt like a deliberate scam. If you don't notice, they will charge you. Everyone, be careful.