MTN taking me on marry go round fro closing a lapsed contract even after I’ve informed them I’d like to close the contract

I cancelled my MTN contract they continue to debit my account, I went to an MTN shop I was given a reference number to call a call centre, they took me from pillar to post now all of sudden I’m getting emails that I’m on prepaid contract I don’t want anything to do with MTN they refuse to close the even though it has lapsed. Their business model of refusing clients their rights is very unprofessional.