Cancelled Contract but still existing

I took a contract with MTN 2 years ago. The contract expired in December 2015. I called as early as October 2015,I was then told to call in November 2015 of which I did. I even confirm with call center lady the last payment. Yesterday the debit order went through and I called MTN yesterday they confirm that the contract was not cancelled. I spoke to my bank to reverse the amount as I did what I needed to do with this contract.I want to warn MTN customers that when you want to leave MTN, they will do their ******* tricks to keep you. Although they have sent their air time, to me I do not have a contract with them as it was cancelled in December 2015. I am not going to pay them. The contract number is ***