As I understand it the issue is still being investigated and must be a complex one if they haven't been able to track it down yet.
The correct username details to use for TV Go should be the primary username for the account. This will be the username that is used to sign into the main My Virgin Media account where account billing information can be seen.
The primary username that VM hold on their systems can be checked via the steps on this help page:
I've now confirmed what my old NTL email (never used or had to use before) was that I needed to log on to my 'primary' account with.
It's let me log on to my account with this email address and then it allowed me to update the password for this old user ID.
Even after waiting for and seeing the confirmation email for this password change (which ironically still came to my personal email address that I would normally use to log on to my account and Virgin TV Go with) there's still no joy being able to log on to Virgin TV Go using this old email address and my updated password for it.
To the best of my knowledge I've only ever used my own personal email address - not an NTL, Virgin or any of it's predecessor email account - to log in to my billing account and everything else Virgin media related.
Thanks for posting and welcome to the community. My apologies for the TV Go issues. I'll PM you now to get some details and if we can't fix it here, I'll pass the details to the team who're investigating the issue