I used 100 on my traditional VM landline and got connected to VM operator services which seems to imply that I was wrong and you were right. I happily stand corrected and I am sorry that I called you out wrongly.. But, as I have said, I am not convinced that testing the number would have got us anywhere further because the fault lay elsewhere.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.