Cancellation still not action-ed after 6 moths

I've cancelled my Telkom Mb line and landline on the 22 June 2018 trough their preferred online method. I've phoned numerous times to stop invoicing me all i get is they escalated it to their cancellation department. I want to launch a dispute but they told its not possible at this as the services needed to be cancelled first. I was told that someone will contact me in a 48 hours to confirm the cancellation. I'm hopeless as I'm billed since June for services i don't use.