I have had Broadband with BT since September 04 and was happy enough. Switched phone over to BT as well from Eircom in September 06 on a 3MB + Line Rental 50 euro a month deal and was double charged on every two month bill for full cost line rental and BB for the November January March and May Bills. Lost count of the number of calls to BT customer service who said it'd be fixed only for a huge bill to come in the following month.
Eventually went to ComReg who told me to go back to BT and give them 10 days to send a letter stating they were refunding over charging. Left it three weeks..no letter...went back to ComReg....got a call from BT following morning and another call the day after saying they were sorry and were recrediting overcharge. No written apology but at least it's some progress after months and months of hassle.
It's typical...you have to go to the regulator to get anything done. Am still waiting until the 24th of this month though to see will the bill show the credit