damaged goods

I bought a 2013 BMW 3201 F30 from CMH umhlanga GM in November 2015. I am unhappy with their method of doing business because I feel it **********. firstly the dealer chose this car for me and when I wanted to take a cheaper car he told me the system would decline me and I will not be able to apply for finance for at least 6 to 12 months . I needed a car so I took this car , on test driving I realised it had a rough idle , I brought this to the dealers attention and he assured that there is nothing wrong all these car have the same noise. I was told the car was still on motor plan but I have discovered that its been in an accident now , already I have taken it in to BMW for fixing 4 times but nothing has been done . The car is full of scratches and seems to have a wiring problem , the lights keep flicking and sometimes gives a bulb failure warning. I told the dealer that I am unhappy with this car and want him to give me another of same value or lower but he told me to bring it in for evaluation and there will be a cash difference that I will have to settle . I feel this wrong , they should redress their wrongs . they are purposely selling damaged cars , CEO PLEASE intervene