Contract Cancellation gone bad

I had or still have a contract with Cell C, i Went to Cell C In wonderpark to ask for a cancellation/ Settlement amount. They gave me the amount to go pay at Nedbank and i did so. i cancelled insurance aswel but now after 2 monuths i recieved an sms saying i need to pay a certain amount, also on ITC Transunion they didnt close the account. This is my second contract with Cell C and the same thing is happening.