Contract not cancelled

Hi, <br> <br> In January 2015 some time I got a called by a sales person from Ghandi(MTN) asking if I wanted to have an upgrade on my contract. REF #: ***. In which I decline and asked that they end my contract and end it. <br> <br> three months later, I get a statement which says I am in arrears. I have now paid the arrears and requested the contract to be cancelled. <br> <br> Gobsmacked by the service and lastly, why cant they credit the account with the amount paid towards the contract. <br> <br> Contrant # *** (Which is now pay as you go)