Not so! Dammit, they've gone and changed it. Maybe they only sell packages now? Not a problem if you already have a BT line.
All I can suggest is pretend you want to change your existing BT BB.
On Home: 2nd Tab at top: Phone, Broadband & TV
Already with BT?: Do I have the best value package?
Then see Just Broadband Option 2 & 3
(dunno where's 1 gone) on R.
Alternatively, if you already have a BT line, I suppose you just merge that into a bundled offering, starting a new contract term, I expect.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU BB => 2010: Orange 16 Meg LLU BB