TELKOM has not refunded me for cancelled service

In November 2016 i app**** at Telkom to upgrade my DSL from 2 Mbps uncapped to 10 Mbps uncapped. After many call and visits to Telkom I decide to get this service from a private company as TELKOM did not upgrade me. On the 10 May 2017 I cancelled my services with Telkom. They told me that they will only be billing me until the 10 June 2017 (30 days notice). Telkom only disconnected part of the service on the 30 August 2017. As of yesterday they still charging me for DSL line and have not refunded me as promised.

Whats recourse do i have to rectify this problem? Its a complete nightmare. Every time I visit Telkom office they say i must call CALL CENTRE. Which i have many many many times :( :(