I would like to raise my concern about the experience experience I had with the sales personnel at Heidelburg Hyundai Outlets

I would like to raise my concern about the experience experience I had with the sales personnel at Heidelburg Hyundai Outlets. I was sold a Hyundai i20 in March and told to put in a holding deposit so that the car will be auctioned the following day. I deposited R3500 to the business account which I was given to by the supervisor. I was told should I not show up to their offices within 14 days the car will be sold and I will be given a refund. To my surprise when I called to inquire about paying the remaining amount within the time frame given, my car was sold to another client. I did not understand how that was done I was told the other client had cash and I will be refunded I shouldn't worry. They said the money should clock in 2 days. As they verified my account. To date I have not received the money and they keep giving me the run around that the manager must authorize it and he has not been at work. Please help me tk get the money back which I deposited and I want to know how does a big dealership like Hynduai sell 1 car to 2 different clients Regards