well tv & internet comes down the same cable.. it does sound odd.
unless their cabinet is full.
Odd as it sounds they have been saying and doing this ever since that were NT? (think that was what they were)
They wont bother sorting the cabinet out and just stick you on an overloaded one that will just handle the TV and it will be crap jutter quality half the time and the line wont be great either.
Been there had that, no net and then changed to sky and pipex when it happened to me. Not the last time I heard it or when it became Virgin too.