Billed incorrectly

I originally called to cancel and was given an option to upgrade and was given a wonderful offer. So i stayed and took the offer. Now that i have received my bill, i have been over charged. I have escalated my issue 5 times with your call center. To date no one can assist me or help me, they keep transferring me to Solutions department. They say they will get back to me. These are the Ref i have for the calls I have made, ***, ***, *** I am ready to cancel and Vodacom have not delivered as they promised. Now they want to de-ativate my service for non payment. :-(