They've likely turned off the phone lines. Used to do it when I worked there. We'd finish at say 1am, so they'd cut the lines off from 00:35am, and then fully cut the lines at 1am.
I too live in a pure NTL place atm. Worked in tech support at NTL for dial-up £1 a min
and original cable modems (Surfboards), and considered ourselves lucky with the speeds and service. However since upgrading to VIVID, I do find the service to be patchy to say the least. I get constant drops on wifi. I would put it into modem mode, and hang a draytek or something off the end, but im too tight to spend the £200 on a router. I could use a cisco 887, I have several, but it wouldn't have wireless. See earlier comment why I wont get a better router, or wireless card ><