VM are moving customers from NTL / Blueyonder accounts over to the new e-mail system. The notification stated that this would be complete by the end of Jan and that you would be told once its done. They did say that you shouldn't have any issues during the move, so this is probably something else.
Edit: I'm still able to access my Blueyonder e-mail (via POP) and Webmail. Although I'm not in your area, might be worth giving them a call.