Terrible customer service

I am disappointed with the service from your Midrand Mercedes Benz dealership. My car is in for repairs. 2 weeks later and they are waiting for approval to repair my car. My car is under warranty. Why do they need approval, and why does approval take so long? Very frustrating. I do not have a car and I cannot afford the R5000 holding deposit for a loan vehicle. I called Mercedez Benz customer service to assist and I am still waiting for them to get back to me. I do not know what to do. I bought this car 6 months ago and drove it for less 10 000km.