Telkom cancellation

I have not had an account with Telkom for over three years, yet they started debited monthly amounts about 6 months ago. My credit report also states non payment as Telkom. I have tried using the portal to cancel, yet nothing seems to happen. I have tried to call but no answer. It is **************** that Telkom can get away with this and make it almost impossible to cancel. The service is useless. Please can someone advise how to ensure it is cancelled for good before it damages my credit rating.