McCarthy Constantia selling damaged cars

We have bought 6 cars from McCarthy Constantia to date wherby 3 cars had to be returned due to accidents, faulty parts ( that could not even been fixed by the agents, second hand parts are being put into the car under your extended warranty plan. Its been 4 weeks now since we have escalated this problem to the dealer principal, the group MD and the CEO of Bidvest. The car has been towed twice now because of the lack of commitment from them to resolve the issue. We are the ones that has to carry the financial implications all the time and we are now stuck without a car no one really cares. I am not sure how McCarthy can be happy with the kind of service that we as long standing customers have received. What is going to be done about this. This goes out to anyone in the market that wants to buy a second hand car from this dealership. Please get a AA report before you buy a car from them.