They are being difficut when i want to cancel my sim contract with them

They are being difficut when i want to cancel my sim contract with them. I phoned them to cancel and it was done successful but end on the month they still deducted when i call again they said the account its still active they dont know what happen i must just pay the money even i cancelled ...consultants not helpfull at all very unfriendly so disappointed with cell c i cant wait for my other contract to expire .