CONTRACT CANCELLATION AND DEBIT ORDER REVERSALS

I am so upset with MTN right now, I have tried to be civil with them and pleaded for my contract with them to be cancelled for months now. I am still being debited for services that I don’t use. Their agents are rude and no one ever assists, all they do is ask for your ID and cellphone number. I understand that they want to retain customers but they shouldn’t do it by force or out of my will even when I want to part ways. I want them to reverse every cent they have taken out of my account ever since the contract ended!!!! Please assist.