Faulty new vehicle CLA45S AMG

I bought a Mercedes Benz CLA45S AMG from Mercedes Benz Sandown Motors Rivonia. The vehicle was a new vehicle and one of the first in the country. I then proceeded to drive the vehicle for about 3 weeks and then it started to show errors with the 4matic+ system. It was taken to Mercedes Benz Sandown Rivonia to be rectified where it spent a week. The vehicle was collected and it still had further issues. From leaks to error messages appearing on the dash board. Mercedes was notified and they sent a technician who assessed the vehicle and they then collected the vehicle and brought back a A200. The premiums were still being debited. The vehicle was returned and the problems persisted. They were notified and we requested that they give us a car similar to the CLA45S as this was what I was paying for. The vehicle was collected and a A35 was brought as a loan car. We struggled to get ahold of the dealer principle for weeks to find out about the vehicle. To date the vehicle is at Mercedes Benz (3 months later) and the matter now has been taken up with Mercedes Benz South Africa. They have written to us but taken weeks to return our correspondence. They denied our request to have the vehicle replaced as we believe the car is clearly a lemon. They stated that they have repaired the car and that it is perfect. We then wrote and said we would take back the vehicle on condition that the faults that previously arose, do not present themselves again once delivery is taken and after driving it within a reasonable period of time. If they do then Mercedes should replace the vehicle. They still have not reverted back to us. The service from Sandown Motors Rivonia is shocking and so is the service of Mercedes Benz South Africa.