German Romantic Road and Black Forest

I have used Zuzuche several times, but this was my first time with Europcar, and it was a very unpleasant experience. I had to wait in line for nearly an hour to pick up the car. The price difference caused by the prepayment was blamed on a discrepancy between their system and the agent's (Zuzuche) pricing, amounting to more than 50 euros. I had to pay their price to get the car. Even the supervisor didn’t take a detailed look or care about the discrepancy and wouldn’t answer the call from Zuzuche's representative in China. Otherwise, they wouldn't give me the car. When picking up the car, it wasn't the one I originally booked, and I wanted to confirm if it could fit our luggage. They rudely said it was the only car left, take it or leave it. On the 14th, returning the car went smoothly. Someone checked the car at the drop-off point, I signed a form, and there were no issues. When it came to billing, a few days later, my credit card statement showed the prepayment deducted, but it was charged in dollars instead of euros, and they calculated it in some unknown way. I have asked Zuzuche about this several times with no response yet. Very dissatisfied.