Service from hell

I purchased a car with your Centurion branch The initial process was efficient, as the sales person.Themba managed to get my application approved all in one day.The were a couple of hiccups after that, but I will address this one that has me absolutely frustrated. I traded in my car to be used for a deposit, the agreement with the dealership was a portion will be given to me in cash. A price was agreed on, I collected my car on the 20th February, I still do not have the cash that was supposed to be deposited to me. I have been fed stories about some person or another not being able to sign the cheque. A full three weeks, meanwhile they have the car I traded in, in their possession. I made a follow up call, frustrated of course, to find out how far the process is, I was told I will need to send a receipt of purchase of my previous car. I told them I have no idea where that is as it was a private sale five years ago, but gave them documents that showed that the car is in my name. Today I am told I need to make an affidavit that I paid of the car, this is very frustrating as I have done my part and given them documents that fully state that the car is in my name. I want my money pls.