Doubled Invoiced and 11 Calls to Customer Service with no Help or Communication.

i have contacted the customer service center from the day i received my invoice, the 7th July, as there were 3 issues on the bill, i was over invoiced on the agreed contract amount, as per the Friday Special, i was then charged a upgrade fee, after the call center agent said on a recorded call there were no additional charges, and lastly, they billed me without passing credits on the old contract which was upgraded. i have called and explained this to 11 consultants with the aim of having this resolved before the debit order ran off my account. , all the consultants promised that this would be sorted out within 24hrs to 48hrs, then i was told 5 to 7 working days, they i was promised by 6 consultants that they would get a supervisor or team leader to call me, as i kept requesting to speak to someone in the accounts department, to explain what was wrong with the billing. Needless to say, the debit order off today, another call was made to the call center, another promise of a manger to call be back and still no communication 20 Working Days Later...........