Incorrectly invoiced and Autopage non responsive

I migrated my contract and was put on the incorrect contract by Autopage. After several escalations they have rectified my contract but not reversed the amount the I was charged in excess. I was advised that this will be Credited in July. On Friday the call centre confirmed the amount that I would be credited and today when I phobe the call centre and the accounts they tell me the credit has been cancelled and keep passing the buck to the other department. I have logged many tickets to get a resolution but I all you get is a automated response. I really would like to end my contract with Autopage. The most pathetic customer service one could get.