Hi Rob,
Loss of downstream is very very rarely a nationwide issue. It would take a amp to fail, power fail to cause a nationwide issue and there would be thousands of customers affected.
Loss of downstream is most often caused by a local issue and will need a tech to check it out. Since you've gotten nowhere with 1st line may I suggest news group support.
http://www.virginmedia.com/myvirginm...setting-up.php
The group to post to is
virginmedia.support.broadband.cable