****** phone / Trying to do a sim swop

My phone was ****** some 4 weeks ago. I have since got myself a new handset to use temporarily but I cant seem to get through to the call center to get a sim swop done - I have tried calling every 2nd day since then without any luck. The number just rings continuous.<br> <br> I have also tried going to an MTN store and they also said they cannot assist because they also have to contact the call center to process the sim swop.<br> <br> My contract was due for an upgrade but I think after this I just want to cancel the contract. My contract entitles me to get monthly airtime and because I do not have my number the airtime is just accumulating and not being used.<br> <br> Please please please help.