Dissatisfaction claim

I bought a BMW 118 E87 engine from Auto Select late in March this year, I complained about the scratches on the bumper and they told me they will fix them, a week late I realised that it had a leaking radiator and I told them about it, they referred me to their mechanic who fixed claiming from the warranty I personally bought. Almost 2 months later the car miss fired and had oil leaks on the engine. Even has a heat system that blows cold air smelling oil from the inside. I reported back to the dealer and their mechanic refused fixing the car telling me that the warranty I bought can pay for all the costs. I told the car to 5 he next mechanic I know in town, Mr Niger who fixed the car for me charging me R 3250 and even now the car is with him because it's still jerking while driving as if it has petrol cut off and I have to pay about R 9000 for him to fix this car for me. I'm writing to you because I need your help, I have spoken to my bank because it financed me on the car but I couldn't get help from them. I even emailed Ombudsman motor industry asking for help but I haven't heard anything from them. I wanted this guys to fix the car or exchange to another car but they refused