CONTRACT NOT CANCELLED

I took out Wifi data contract with Telkom, only to find that the sales person did not check that the area I live in does not have coverage, The next day I go to the PAVILLION branch and cancelled the contract, filling the cancellation form and returning the device and left with the assurance that the cancellation was done . <br> <br> 3 months later I am being billed for a contract that has been cancelled, I visited the branch 4 times and emailed , Telkom more that 5 times , been given the run around . I don't know what to do, is this how Telkom does business, I am disgusted that after all my interactions with Telkom , I have had no resolution , please help me. This inefficiency is NOT acceptable.