CANCELLATION OF CONTRACT!!!!!!!!!!

Good day can any one please explain to me why its so damn near impossible to cancel my contract with MTN. I have beeen trying non stop since January to cancel my contract. I phoned MTN the first time to cancel my contract where I was given a ref number and told it was cancelled. Come month end MTN deducts money yet again. I phone again and was told someone on their side never finished the cancellation. So I was given yet ANOTHER ref number and told this time round it will be cancelled. Month end yet another deduction. I phoned again and also e-mailed my cancellation to them. After phoning again I was told it was still at the cancelation department, the gentleman put an urgent mark on my contract and said he could not give me another reference number as to many numbers was linked but promised it will be resolved immediately. Month end ANOTHER deduction. After various more calls and mails (no one responded to my mails) throughout this year I am still being charged for this contract. I was phoned now for an upgrade were I completely lost it because I DO NOT WANT AN UPGRADE I WANT A CANCELLATION. What is so difficult in understanding this. I have had enough if MTN does not resolve this issue I will make a case with the police for theft if they deduct again. This is ridiculous!!!!!!!!!