bmw unreasonable and unresponsive

I bought a BMW I two and a half years ago and have complained constantly since then. I had two accidents caused by the fact that there is a complete blind area when you turn a corner or a traffic circle. earlier this year they had the car for almost 3 months as they could not repair a major fault with the automatic car jumping out of gear and stopping dead in the middle of the road. I got the car back and it now has a major leak in the engine - they keep putting me off when I bring the car in. I feel totally unsafe in the car and wanted to change to either a second hand mini or a Honda. Honda offered R170000 on the car as a trade in. BMW finance have now advised that I would have to pay in R70000 more than the value of the car to get out of the car. I have been paying more than R5000 per month for two and a half years and cannot believe I can still owe this amount of money. I believe they must be contravening the National Credit Act as well as the Consumer Protection Act and have written to them numerous times with no success whatsoever. They keep just putting me off. It seems to me they are also being ***ist as male colleagues get much better service from them.