At first, the staff admitted that I had prepaid all the fees and said they wouldn't charge me again. But I immediately received a notification that my credit card was being pre-authorized for $1000. When I asked them, they told me to call the headquarters. The headquarters staff on the phone said the car rental company hadn't received payment from the rental platform. I called the rental platform, and they told me they settle accounts monthly with the rental company, and assured me there wouldn't be double billing. But in the end, I was double charged! Although the rental platform eventually refunded my money, I lost time and suffered from the exchange rate disparity!