MTN allowed ********** transactions on my account, not following FICA requirements, and continue to charge me - over R5000 so far!!!

MTN SA have, without my authority, charged my account with 2 new expensive contracts, have allowed the ********** change of my address on their records and delivered 2 x iPhones to the perpetrators of this *****, and now expect me to jump through hoops to sort this out. MTN's inept staff allowed this ********** activity without proper FICA processes being followed. I have so far been billed (and paid) over R5000 on a debit order, despite corresponding with MTN for over a month to credit my account with the unauthorized charged. Their Group CEO Ralph Mupita and MTN SA CEO Charles Molapisi don't even have the courtesy to respond to emails or delegate my complaint to a senior official. I have corresponded with MTN over 6 times within the past month, and am no nearer a solution. Any advice shall be gratefully received.