Telkom bills for non existent service and UNABLE to cancel the service

Help! I was a loyal customer of Telkom for over 30 years. Due to a fault on my line which was never fixed, I cancelled. However, I have been billed ever since for a non-existent service. repeatedly I call the billing department and am told that my cancellation has been 'escalated'? But this service is just never cancelled and my monthly invoice arrives by email every month with a greater amount each time. The staff at the Telkom shops are unable to help and can only sell new services and contracts. Not willing to add my ID number as I see Telkom does not respond on hellopeter.