I've just got Virgin Media cable TV (it used to be NTL).
Under interactive services you can even order a pizza. I'm not planning to do this, but there's a box where you have to enter your postcode, and I can't work out how to enter letters with the remote control.
It's the V box that came from Virgin, and it's the remote control that came with it. There are number keys with letters on them, but if for example I press 2 twice I get two 2s, not an a...
I have just turned my virgin box to see - try pressing ok when the box appears - this should bring a keyboard up on the screen, which turns your numbers to letters.