Telkom unhelpful and charging for a cancelled account

Our company did not receive an invoice from Telkom and yet an account was handed over. We paid the amount as per the letter send to us by Telkom and cancelled the account with Telkom. Seipathi Sekabate from Telkom confirmed in writing that the account has been cancelled. But yet once again we receive a message from NuDebt saying that our Telkom account has not been paid and handed over to them.

Seipathi Sekabate from Telkom does not response to messages and we have no idea what the outstanding amount is for.

IS THERE SOMEONE AT TELKOM THAT IS WILLING AND ABLE TO ASSIST WITH THIS MATTER???