incorrect billing

I app**** for a fixed line with Telkom. Once installed I cancelled my 2nd number with them ***) with the help of Brian Graaff in Alberton City who kindly emailed the cancellation for me on 1 December at 2 39pm. I have luckily a copy of this request which I have emailed cancellations department many times before including [Email Removed] who promises to cancel the number in question. to date I receive a bill every month for two numbers and they are charging me interest on outstanding balances. I really do not know who to talk to anymore to resolve this matter