Cyber Bullies?

In or around the 23 March 2020, I gave notice of my intention to cancel the landline service I was receiving from Telkom. By my reckoning I would not pay rental beyond 24 April 2020. As it happens, I paid the line rental up to and including 24 May 2020, a full two months later. My notice was acknowledged by Telkom on 15 May 2020, followed by a further acknowledgement dated 19 May 2020, warning me that until I received confirmation that my “order” was completed, I should continue to pay. Telkom indicated that it was my responsibility to cancel a contract they had with my ISP supplier, which I tried to do, to no avail. Considering that the contract was between Telkom and MWEB and that I continued using my ISP supplier for the full service, I did not see it as my responsibility to cancel the contract on their behalf. Through various debt collectors, Telkom have been pursuing me for line rentals ever since. Each time I have sent an explanation to the attorneys handling the matter, they have backed off. Until, that is, when NuDebt took up the cudgels, ignoring my explanation and threatening with blacklisting and legal sanctions. The notices from NuDebt are received regularly, each time apparently from a different person. It appears to me that the threats are bullying tactics designed to scare me into complying and borders on a ****