I got this same problem this morning. When I headed over to My Virgin Media (as instructed), and selected "Sign In" there was nothing about "Forgotten Your Email or Password" on the screen. I even cleared my cache and cookies to ensure I was going to the correct page, but no joy - the instructions and page it linked to did not match. I had to trawl through a dozen thread on this forum to find a link that took me to a page where I did find a "Forgotten Your Email or Password" option (which I assume is where the link on the email unavailable notice should have taken me to!).
It would have been really helpful to me, and saved a lot of worry and time, if the instructions on how to reset the email and the page it linked to actually corresponded with each other 😞