Tried all the suggestions on the Virgin Media website.
Run three "diagnostic tests" today - all say no fault. It is not my phone itself - my parents phone is also off (live nearby) - how soon will it be fixed? Service status says no known issues in the area.
Happy to hear it's now working for you JL23 and thanks for updating us. Sorry to hear that there was no explanation but please monitor it and let us know if you get anymore problems so we can look into it.