Looks like there might be some teething troubles with the upgrades
http://www.theinquirer.net/?article=30755
EDIT:
And BT have come up with a nice scam. Get an upgrade but by accepting it you will be locked into a new 12 month contract
http://www.theregister.co.uk/2006/04/05/bt_broadband/
Bet Ntl are kicking themselves for not thinking of that one.