MTN DOES NOT CARE

So after all my complaining and e-mails and frustration and anger, this company still just ignores me. My credit rating has taken a dive because of their incompetence. I have mailed the retentions department with all my details and asked them to cancel this contract and asked them to close my contract and to send me the settlement figures so I can get rid of this headache. They simply ignore my requests and continue to bill me. I have been forced to contest and reverse these debit orders and still they do not contact me. I don't have the finances for a lawyer. Can someone please advise me on how I can get rid of this MTN nightmare?