Telkom cancellations

Telkom is useless. I cancelled my service with them on 02 May 2018. I keep receiving accounts. I queried it with them and receive message that your problem has been resolved with the following number *****. During January 2019 I received communications from a Debt collectors company. I proofed to them that I have cancelled. They made me complete a form. Now 7 months later, a new company has been put on the case and I am once again being harassed. What do I do now to resolve this. There is not one human being that you can communicate with. Telkom stores refer you to the internet. What now!