Avis/Zeda are ******

I hired a car from Avis/Zeda Car Sales for two consecutive months, on the third month, I paid R15 000 and immediately after I made the payment, I was told that they could not close the file for the previous month as I owed them and so I did not receive the car that which I was paying for. They made me complete and sign a refund document on the 15 of May 2024. It has been close to two months now since I made the transaction, I have not received my money back, I have submitted all the proof, to them and that includes my bank statements, my proof of payments and a letter from my bank indicating to them that they did receive the money that they allege I owe them. Worse, they have been saying that they are investigating the matter, to this day no one has come back to me, they're not even responding to my emails, emails that have all the proof that I submitted.