incorrectly billed and no effort to correct matter

After contacting vodacom last week regarding how they have incorrectly billed me and debited my account after I had settled and closed one of my contract, I paid in extra to ensure that i would not be invoiced for another month but found myself a couple of hundred rand short on a contract that I had closed. After being on the phone for most of last week 3 June and being sent from one department to the next I am still waiting. I even have a refund reference number but still I wait for vodacom to give back my money.