Dishonest Motor Dealership

In July 15, I bought a 2005 BMW X5 from this auto dealership and within 3 days started experiencing one problem after the other. The vehicle underwent a complete scan at BMW and replacement of coils to radiators etc, was done which cost me about R30,000 in addition to the R124,000 cash I purchased the vehicle for. After numerous attempts to get it sorted out with the dealership the only response was that I signed that the vehicle was in good condition upon purchase and driving away with the vehicle. Also that had I taken and paid for a 24mth guarantee/insurance with them then it would be covered, which at the time of purchase I told him that I was going to think about it and revert. How on earth was I suppose to know that it had underlying faults, as prior to purchase I was guaranteed that all was in good working condition. Up to date I haven't received any positive feedback from the owner and I feel he keeps on avoiding me. This is extremely annoying and frustrating, cause though it's a secondhand vehicle, one still expects it to be driving and not completely stop in less than a week of purchase. I found Lawrence to be dishonest and not fair whilst conducting his business.