I bought a 2nd hand car with endless problems!!!

I bought a second hand car from Brits Nissan in August 2014, after we took delivery of the car we started having trouble with it and took it back time and time again to have the problem sorted out, now 8 months later (of which the car was / still is in for repairs a total of approximately 4 months) we still have the same problem with the car, now it came out that there is accident damage on the chassis as well as the engine of the car, which we where never informed of! I have tried everything to have this contract cancelled with both Brits Nissan as well as Wesbank and I have hit a brick wall with both of them, We now sit with a quotation of over R 40 000.00 to have the car repaired and then it doesn't even include one of the problems that we have had from the beginning.