MTN WON\T CANCEL CONTRACT!"

My contract expired end April this year and I assumed that would be my last payment. But MTN kept debiting me. I sent numerous queries online and emails and tried to call several times to resolve the issue and even try to cancel the contract (which I realised I had to do after re-reading my contract) but NO ONE got back to me. Now they are saying my account is overdue and have suspended my outgoing calls and data usage. They won't even cancel the contract I have so the contract is STILL active and what makes matters worse is I get calls from their call centre offering a new contract plan which I have clearly stated I DO NOT WANT. I have been trying since May to call these people and this mess would not be on my plate if someone had bothered to have the decency to pick up the phone and contact me to resolve it then or even answer the phone when I call! The worst service I have ever received especially since my credit record is being affected too