I have exactly the same problem. Been trying to register my new virginmedia account for the last couple of days to no avail. It doesn't let me go past first page where you put your surname // account number // area code. Or when it does you get a message "ooops something's broken."
"We're sorry this isn't the page you wanted.
This part of the site isn't working at the moment, but it'll be up and running again soon.
Other parts of the site might be working as normal, so try using the links below to help you find what you want."