Cancellation of the contract - account no ***

I had a contract with Telkom which has expired but starting from last year April I have been sending them cancellation form but nothing happens. Even today I was speaking to the agent at the billing department asking him to check my profile as in why am I being billed even if I have submitted the cancellation form more than once the best he could do was to put me on hold I requested to speak to another person I was on hold forever and to told to keep on submitting the cancellation form which is unfair to me because the money that I am being billed I could have bought my kids 2 loaf of bread