Is it possible to cancel a Telkom contract???

Tried to cancel over the phone, this does not work since they don't answer. Called the call centre, they said I have to go to the shop to cancel. Drove 100km to a branch and completed the cancellation forms, this was over six months ago and still being billed. Complained on HelloPeter and they rep**** that they would investigate and reply as soon as possible (***), this was 3 three weeks ago and no feedback.