Cancellation of contract

My data contract with Telkom ended last year around June 2017, and July I sent my first email to cancel my contract, and September my contract was still not cancelled and I called the call centre to get it cancelled and I was told to send the email through to ********** and nothing happen, I even went on to their twitter account to raise this and even there nothing helped, so now I dont know what I should do to get this contract cancelled??Please Hello Peter help me resolve this, as I cannot afford to pay this every month...Account number ********** 10 cell number ********** 125