Unaccountability

I am so disturbed by the service received from Mercedes Benz, on 3 different occasions my vehicle has showed the engine light error. They send out a technician who cannot find a fault. My vehicle has gone in 3 times to various Mercedes Benz providers just for me to get the vehicle back with the same problem. I also called the Mercedes Benz South Africa who told me to take the vehicle to the branch where I purchased the vehicle they should then do a diagnostic, if they dont find the fault, they then have to get in the technical department and lastly they should call Germany if they also cannot find the fault. This always happens when I am on the long round as I am a business woman. What happens if I get hurt while waiting for a technician, what if my car goes into limp mode putting my life as well as the lives of other road users at risk. I hold on for such a long time when I call the call centre without anyone answering the call. I am at my wits end and have decided to revert myself to this platform maybe then something will be done.