Still being charged for a cancelled account

I submitted a cancellation request form on 26 October 2017 to have my Telkom account cancelled at the end of November 2017. I received confirmation that Telkom had received my request.

Since then I have been charged my monthly amount (originally R199 and then increased to R233) and every month I try call Telkom to ask why my account has not been closed. I've never gotten a clear answer but was assured last month that the account had been cancelled. As usual, I now have just received an invoice for April 2018.

I also have a dispute outstanding (reference number: 285 186 31) which was lodged on 11/01/2018.

I would like to know what else I need to do to cancel this account and how I can get my money back for all the months I have been charged ********ly!