Cellphone contact cancelation

If I could rate them half a star or none at all I would, my experience with having a cellphone contract with MTN has been horrible and stressful, paid off my account on the 27th of august, when I tell you MTN tried to debit not only that payment has not reflected and I have sent multiple proof of payments, to make matters worse my calls have bee suspended so I cant call, and ive been handed over to collection plus a late fee meanwhile I have paid the full amount to close my account its as if they intentionally dont want people closing the contracts.