Telkom account handed over to lawyer even though TELKOM stopped the debit order because I cancelled my account (and they acknowledged it by stopping the service on the line)

My account was cancelled as per Telkom's procedure (signed cancellation form and attached copy of account holder's ID) sent to cancellations email in March 2018, the email was acknowledged by Telkom and the cancellation was to take 21 days.

The line's service stopped working - great, Telkom obviously received the request.

Our account was debited for several months after that, after numerous calls and sending the forms again and again, the service was cancelled (the line no longer worked) but our bank account was still debited. Later in 2018 our account was no longer debited (yay) and we thought Telkom had communicated the message to their accounts department that our line was cancelled some months prior (finally).

Today, 18 January 2019, I received an email stating that I've been handed over to a lawyer and that I have 28 days to pay or else they will black list me.

In summary, I was paying for service that I was not being provided with for months but could not get Telkom to stop debiting my account. They then eventually stopped as I had correctly cancelled my account and now they want to blacklist me for not paying, even though they were the ones who stopped the debit order... as per my request... because I cancelled my account.. quite a few months before that.

Is there anyone in Telkom that can simply look at my cancellation email, and tell everyone in Telkom, and their lawyers, that I should not have been paying in the first place (and they can't deny it, because they stopped my line as per my request), and help me not get blacklisted?