Upgraded and charged without authorization

In the beginning of October I saw on my bill that I was charged an additional amount due to the ADSL line being upgraded which was NOT REQUESTED OR AUTHORIZED.

On the 13th I called billing and was told to speak to sales as they upgraded the line. On the 15th I emailed the sales consultant in our area, Linah, who said that the minimum package is 4mb and all lines are being upgraded for free and we should speak to billings as it should not have been billed.

On the 19th I called sales again to confirm this and spoke to Jess who said there was no order for an upgrade or billing change on the system and she transferred me back to billings. Toza answered and referred me to her manager Nomi who said she would find someone who could investigate the matter properly.

To date I have not had any feedback and I want to cancel my account with Telkom completely ASAP! Do you think I can get hold of anyone to assist me!?