Wrongful Billing of Data & No Interest to Rectify

Earlier this year I upgraded my existing contract with MTN. Bradley in the Cape Gate branch helped me with my upgrade from a Top Up to a My Choice contract as he advised that the call rates would benefit me. He was incredibly helpful and professional and was the only reason why I took the phone and contract. I was very clear in my request for any and all limits to be set so that my new contract would act as a Top Up contract. I have been billed for data after I was assured that limits were set. When I called the call centre they all say that they can do nothing as the limits were not set by the Cape Gate branch. I then asked them to set the limits as it should have been done to begin with. I then contacted Mr Kriel, the area manager, who informed me that limits set by his staff are not guaranteed and that it is the customer's responsibility to ensure that it gets done. I have made many attempts to get hold of Bradley, but the number only rings and when I do get through he doesn't return my calls. I have also submitted a complaint via the website and no one has bothered to get back to me. As a paying contract customer of MTN for many years I deserve better service than this!