Telkom Cancellation Nightmare

I cancelled my Telkom service in September 2017 due to moving to an area (beginning of October) which didn't provide the service levels I provided. Even though I received an SMS saying the service was cancelled, I was still being charged for an service I haven't used since 29th of September 2017.

I have sent numerous mails to the right Telkom address, without any response. I received a call in March (after numerous conversations with the debt collection agency - sending them proof of the cancellation) that the account would be amended. I received the same bill again. I don't know what to do anymore.