Thank you tom for this thread as I've had two calls from this number today, even though I told the caller the first time that I wouldn't be giving out any personal detail to anyone who calls me out of the blue, and knowing that it was a genuine VM call has put me at an ease.
Aside from the point of the unwanted call, the first caller said her spiel so quickly that I had to ask her three times to tell me where she was calling from and her reason for the call and I think she put the phone down on me when I told her that I wouldn't be giving my details, so the telephone manner needs attention Virgin Media.
Furthermore I can recall making my preference to not receive marketing calls some years ago when I kept getting calls about Virgin Mobile (a service I don't have).