Telkom does not empower its consultants

I cancelled my Telkom landline in October 2019, but still get an invoice every month – six months after the cancellation. The online consultants at 10210 are professional and try to be helpful, but they are not empowered to do anything except listen to a complaint and to give standard answers. That is possibly just as frustrating for them as for us. -- Our landline service ceased to exist in October 2019 when cables in our area were ******. No landline, no internet. On 17 October I send my cancellation order, on a letterhead and with a copy of my ID attached. But I still receive invoices. On January 14, 2020 I telephone and am asked by the consultant (who seems a bit higher up in the hierarchy) to forward my email to her. This I do, and I get a reference number soon after saying that my query has been resolved. Yet the invoices keep coming. Yesterday - 14 April 2020 - I receive yet another invoice, and I phone again. I speak to a consultant who, as I have said, is professional and patient, but who is not empowered to do anything except to listen to my complaint and to give the standard answer. He follows up on the reference number for my query of 14 January 2020 and tells me that apparently my query has not been resolved yet. At the end of the call he asks me if I want to complete the standard questionnaire on Telkom's service. I tell him no - why? Because although his service as consultant is fine, Telkom's is not, and Telkom is only going to ask me about the service I got from the consultant. If I say "Yes, the consultant gave me good service", Telkom will certainly use that to flatter themselves that they are a company that gives effective service instead of doing what they are supposed to and cancelling my line.