I have a mobile phone contract and internet connection with O2. I’ve had the internet connection with them since January 2008.
I have contacted their customer services department several times by telephone and have found them to be very courteous and helpful each time I have phoned.
Why not just give them a call to explain the issues that you have? I’m sure that they will do their best to resolve your problem. Their number is a freefone number so the call will cost you nothing.