Do you work for Virgin Media
When I upraged to 20mb I did it over the phone. They basically said on the phone.. that's it done you'll be on 20mb tomorrow. They never mentioned I might need a new modem.
As for the link you posted, it's hardly in big Bold letters at the top!
OK I admit I should have researched it a little more, and it's my fault I wasn't getting the 20mb service I was paying for. However they didn't exactly make it obvious, especially if you didn't read the website info. I still think there are going to be thousands of 20mb customers out there non the wiser to why they can't get 20mb.