Car Registration Certificate - Advise

I bought a car at , Smith Luc Auto, located at 71 Albertina Sisulu Street, Betrams, Johannesburg, as per below information with Mr James (Surname unknown). Upon collecting the car, he gave me the licence disk registration, the contract of purchase and receipt only. That was the day I went home not realising that the disk had expired. I then contact him and said I should just go to Licencing department and I can have it renewed and also he said they needed about R1800.00 to register the car under my name. I told him if that's the case, he must give me all necessary documents so that I can register the car myself as did not have more money at the time. Unfortunately the car broke down while I was in Welkom and was since at the panel beater it be fixed. The car is ready for collection and I need to go and collect it. I called him again on the 24th November 2015 to advise him that I need Car Registration Certificate so that I can have the details registered under my name but he claims that he had already given me the Car Registration Certificate of which I do not have. I'm unable to register the car under my name, nor to renew the disk.