Cancelling my contact

I have been calling the call center to cancel my contact but till today my contract is still active and MTN is billing my account and every time when I call I get a different ref numbers. First I spoke to Mahlako ref number: *** on the 11th Oct 2015 to cancel my contract but she didn't do her work by submitting my request then ***** was commented with my details where by someone upgraded using my details had she cancelled by contract when she was suppose to this wouldn't happened. Reported the issue at MTN Sandton and Southgate. Then called again and Spoke to Akhona Delman ref number: *** she said she will call me back with feedback but she never did. Called again and spoke to Andrew Crouch who was useless he only spoke me 26 mins later that the system was down. Called again and spoke to Palesa Legodi Ref number: *** who said will provide feedback within 3-5 days till now no feedback. Had to go the bank again to reverse the money debited from my account and because my other debit orders bounced I owe the bank R 155 who will pay that.