Cancellation of Services

On the 15th October 2017 I have cancelled my services with Telkom. On the 25th they acknowledge receipt of it. They keep on billing me. When I phone them they say that they haven't received it. The cancellation documents have been emailed to them 5x now already. They have suspended my email account now because of non payment. This email address we have got since 1988 (business account) and we are paying telkom every month to use this email address which is ********** They do not want to activate it because there is an outstanding amount which I refuse to pay because I have cancelled the service and no longer using it and they keep on billing me. I have disconnect the service myself at the wall. Who can I contact regarding this. I asked them this morning for a managers contact details but they said there is no managers.