Unauthorised upgrade done on my account

Telkom sales department processed an upgrade on my account without my authorization. I have been trying to get this resolved for almost 2 months, without any progress. The billing department will not take any responsibility and blaming the sales department and vice versa. I have been to the Tokai, Blue Route mall and Kenilworth center however they cannot assist in store with billing and sales complaints. I refuse to pay for a service I never confirmed.