Follow up
An incredibly nice chap just called me from NTL to further explain the cause of the problem.
In summary: They havent been charging me for broadband for months and months so when I unplugged my modem for the first time in about a year, when it made a request for an IP address, the system flagged it up as a 'Hey whats going on here?' moment and cut the service (at least thats what I understood, i was at work and I keep getting bombarded!).
So in addition to the credit thats been put on my account, I havent paid for broadband for god knows how long.
Im going to dig out the bank statements when I get home and have try and work out just how long. You know what its like. The mrs handles the bank statements. I just put money in at the end of the month. She just sees NTL on the statement (presumably for the phone) and thinks everything is hunky dory.
Anyway, I have to give a thumbs up to the CS department on this one as, once the problem was identified, they have rallied and given me a more than satisfactory resolution. Very courteous and helpful. And the manager type guy even gave me his direct dial incase of any other problems
A rareity!
Hopefully this issue will filter through to the tech support incase anyone gets this in the future.
So thanks to all who have helped me out over this especially Simon M and HD.
Cheers!
