Still being billed after canceling contract

I have attempted to cancel my Internet subscription with Telkom on 19 September 2018, as I am no longer working, and have been through the most harrowing nightmare since! Despite receiving a cancellation number, Telkom continues to bill me every mo month! To date, they have **********ly deducted over R13000 from my bank account. All this from an unemployed person! I have called their call centre several times since October 2018, each time I speak to a different agent who tells me that someone will call me within 48 hours and my matter will be resolved, but this never happened! Yesterday, someone called me from Telkom to tell me that I need to pay a further R4752, to cancel my contract, after they already took R13 000 **********ly from my account!!! Is Telkom for real? I just want to warn people about the pathetic and ************ service of Telkom. I will be going to every possible media coverage to report this matter as they have no intention of refunding my money and resolving this issue!