Continued Billing after Service Cancellation

I have been struggling to cancel a Telkom ADSL line since 2016. I have tried numerous times to cancel it and they just dont and continue to bill me. The last request I sent was in January and they are still billing me! I just phoned the call center to log a dispute and was told I must just wait for Telkom to send me a final bill, I asked "how is that a solution, I have been waiting 3 months for a final bill and its still not coming...?" I had to insist repeatedly that she actually log the dispute. I find it hard to believe that Telkom is still so useless after years of complaints from the public