Cancellation of contract

My contract came to an end with mtn and I phoned the call centre to terminate my contract in December 2015, the agent said it will take about 7 working days for the contract to be terminated but that never happened. <br> I phoned again on the 13.01.2016 to cancel the contract and was told the same thing that the contract will be terminated within 7 days but still up to date the contract is not cancelled. <br> Please cancel this contract.