Dishonest and unprofessional

We bought our first car in March then it started giving us problems after two weeks. They took it back after months of poor communication. They gave us another car which had much worser problems than the first one they never mentioned that the car had been in an accident two times we even provided an accident report but still nobody knew anything and they never disclosed this. They promised us a cash back of R1000.00 every month for 12 months as an apology for the first car. It’s our fourth month now and still no cash back apparently it was never approved. When we communicate with our sales lady(Faith) she tells us that it’s not her problem she doesn’t work with mechanics. After they get their commission they just ignore you. We’ve been trying to call the manager Mikhail no answer. The finance manger Lynna pretends as if she doesn’t know anything and puts the blame on others when she’s the one that confirmed that the cash back will be approved by the dealership. It’s been two months now and the car’s still giving us problems. We’ve been waiting for a courtesy car for weeks now. When we call either they don’t answer or nobody knows anything. At this point we just want to cancel our contract with the dealership.