Refuse to sort out payment queries

My wife renewed my son's contract approx 3 months ago. At this time she was informed that Top up contracts were no longer available and requested a limit on the bill to the contract ammount. This month we received a bill relating to data usage of around R8000.00. On querying this we were told that the phone user NOT THE CONTRACT HOLDER could change the limits on the phone. We stopped the debit order and paid all the phones on the contract excluding the data and sent a email to MTN customer service. Response was - MTN IS CORRECT YOU MUST PAY and phones were suspended. Sent a new letter addressed to MD / FD. asking why the phone user and not the contract holder can change limits- AGAINST CREDIT ACT. Why was the overall account allowed to go to double the limit given by Mtn - AGAINST CREDIT ACT AGAIN. Thirdly why were we not informed that the user could change the limit put in place by the account holder - AGAINST THE CONSUMER PROTECTION ACT. We also approached Mtn Cavendish - Kashan. He said he would see what can be done - STILL WAITING. Also phone his area manager Izak Joubert *** Numerous time - No answer - Left mesS. BOTH MTN CUST SERV AND CAVENDISH NOT WILLING TO HELP.<br>