No response from Telkom

I have been struggling to cancel my contract with Telkom since November 2015. I have visited the branch, I have called the call centre and all these departments assure me that my account is closed. I have written on their facebook page and keep being told I will be contacted but cannot get assistance. Each month I get debited and start querying this and each month I go through the same scenario with no solution. This seems to be a common problem as numerous people have informed me that they have had to go as far as close their bank accounts in order to prevent further debits.