Telkom blacklisting me for a product I did not use

Telkom is as terrible as everyone says they are. I got adsl from them in 2017, their wifi worked 2 days that whole month and I was billed for a telephone that I did not receive til this day, I reported the matter back to them and has been an issue cancelling the contract ever since, I’ve been getting billed every month and they send their collectors to phone me every other day demanding money from me. I’ve been blacklisted because of telkom