Cancellation nightmare

Cancellation nightmare!!!!! I gave cancellation notice in February assuming that my last debit order will be effective end March 2020. We are now in October, yet I am still being billed. In April, May and June i reversed all the debit orders, as Telkom was not entitled to the money. In July, I received a call stating that the contracts have been cancelled and there will no longer be any debit orders. I even queried whether I should close my account and was told that I should not. In July, there was no debit order.

Come August, the debit order goes through again; I once again reverse the debit order.......does Telkom even understand the bank charges involved??? In September, I had no option but to close my account as I received yet another statement. Today (10/10/2020), I receive a letter of demand dated 26/08/2020 for an outstanding amount. There's no contact number for the legal department nor an email address.

Telkom has confirmed that my account was closed on 14 February 2020. So why am I still being billed?????