No contractual airtime on my phone

Over the last two months I have not been able to use my contractual airtime. My data is loaded and can be used but I cannot make any calls unless I load prepaid. I have made 18 calls to MTN, 2 to technical at customer service request and 1 to network only to be told rather rudely that it is not their problem, customer service must sort it out. 15 calls to customer service have not sorted anything out. Last month after 11 calls requested to speak to a supervisor, was told none were available but one would phone me back, a month later I am still waiting for that call.<br> <br> Either customer care don't care about customers problems or they are just not capable of sorting out the problems