Impossible to Cancel Telkom Contract - don't sign up for any services

It seems impossible to cancel a contract with Telkom. Toll free number does not work most of the time, and when you do finally talk to someone, they say that some will contact you withing 48 hours to cancel. That was 4 weeks ago and I am still waiting, while being charged monthly. I have jut received another invoice for R839, when y monthly subscription is R225.