Terrible Communication and Slow Processes at Telkom

Last year in August I sent through a cancellation form to Telkom to cancel the LTE product I had with them. I called the call center numerous times thereafter as well as sent multiple emails to find out when the cancellation will be done. All I was told was that this was being processed and I must send the form again and that there’s a 30 day notice period and that I would be debited for September as well. However, the cancellation was never processed as I was still being billed every month. Therefore, due to the slow processes at Telkom, I started reversing the debit order that was going off my account every month from October onwards as I was not using their LTE product and they had not cancelled my account despite me following the correct process. Today I receive a call from a debt recovery company where the guy explained that the cancellation was not processed because I had reversed the invoice for October which was apparently a cancellation fee of the same amount as my monthly invoice of R699 (which nobody told me about). And then he threatened me to say that I need to pay the entire amount due from October onwards which is almost R4000 otherwise they will blacklist me. I find this to be so unfair as I was never told about the cancellation fee and I have not been using their product from September. And now I’m being threatened and forced into making full payment for something that was not any fault of mine. This is unfair and I cannot afford the full amount. How can a company just do as they please and blacklist someone even if the customer is not the one in the wrong?!