dial 150 or 0345 454 1111 and follow the prompts to - you are thinking of leaving us - dont worry about that they do much more - open 'till 8pm - 6pm on saturdays - closed sunday and the plus is its a UK call centre
talk to them but you will not save a lot of money if anything - the line rental will disappear from your bill but the new package will be repriced - will probably start a new 12 month contract
I have broadband and phone, no TV, and the last time I checked it was cheaper than taking just the broadband (presumably on the basis that they hope you will make lots of chargeable calls); so check carefully before proceeding. I don't know what the situation is now, and it may be different for you, but you might end up paying more for less;
I found it I think.It ranges from £32.50 a month up to £50 depending on which speed and data allowance etc you need.Plus a £14.99 one off connection fee.Now to see how that compares to having it with a phone line!