Refuse to supply car register papers after sale

I bought a car by above dealer on terms. I had so many problems with the car, but eventually paid it off. They gave me a copy of the license paper when I paid the deposit. Now, after a month and half after paying the car in full, they seem to have lost the papers of the car. The owner Erens Uys, just make promises, but never deliver. He blocked my nr on his cellphone. I just want him to give the papers or pay me R20000. The price of the car was R25000.