Telkom Cancellation and accounts

Telkom Accounts Department is useless. I been trying since August 2019 to get the services cancelled and Telkom keep on sending me invoices. In February 2020 I received email confirming that the services was cancelled backdated 04 September 2019. Now I am getting threatening calls and text messages from attorneys that I owe Telkom money. Call the call center and could not get passed the agents to speak to supervisor. Agent promise that supervisor will call back. Still no reply.