Telkom Landline - cannot cancel, Telkom don't know how.

I cancelled my old landline in previous premises in July, using the call centre (gosh I hate trying to use the call centre, it is terrible). I cancelled it online in August. I cancelled it again by registering a dispute (billing) on 30 August 2018. Dispute Ref ********** 7 No luck so far. The bill just keeps on climbing and I am not paying as it is meant to have been cancelled !

OK Telkom, how about cancelling this line and the outstanding bill back to July. I know you can do it, it just takes a bit of effort.