both branch and call center

my contract ended on the 22th December 2017. apparently i was supposed to call them to cancel my contract then went to the branch on the 10th of jan 2018 cmto cancel the contract they th3 manager assisted me to call their call center to cancel my contract then the Zama khumalo from call center they confirmed that the contract has been cancelled and they winy be debiting my account .. boom on the 1st of feb 2018 they debited my account again i called them on the 2 Feb then the lady by the name of Zanele told me that the contract us not cancelled i need to call again on monday she can see that i called but the contract is not cancelled. went to the brance again the manager told me that there is nothing he can do about it since i dont prove that i have cancelled... please MTN i need that contract cancelled n want my refund.... just stop *********** people's money. just want that contract cancelled please