Unable to cancel my account

Since November 2017, I have been trying to cancel the account i have with Telkom. I have sent all the requested documents to 4 different people at Telkom including cancellation ********** I went to Telkom branch in Witbank which they were also useless, they could not help. The account is still not cancelled, Telkom is still billing me. Surely it is not difficult to cancel an account?