Charged for a sim card not in use

Good Evening,<br> <br> After trying to get hold of someone at the call centre and leaving a message on Facebook, I am not trying here as a last resort.<br> <br> I have a contract account, the sim card issued with the phone has never been used, yet my bill has gone from R699 per month to over a thousand. I think someone has ****** the stored sim card.<br> <br> I need someone to either explain these charges, or help me cancel that sim card as a matter of urgency.<br> <br> I do not know the cell number attached to the sim card as it has never been used.<br> <br> i would appreciate a prompt response, this is causing a lot of stress and I do not know where else to turn.