The same should apply to broadband. Read that thread i posted link like the last 10 pages. It will give you some idea.
Click MY SKY tab
Click on link which says "Household marketing"
Then make sure all 3 boxes are ticked.This way Sky can contact you
No weaker position at all. You are switching to freeview,apple tv,now tv etc
Over 400 pages off haggling with Sky here.
http://forums.moneysavingexpert.com/showthread.php?t=2652651
Notters
Once you cancel log onto your Sky account and you should be offered 50% off for 12 months. Hold out like i did for 60% off and £50 bill credit.
You will be given a cut off date for tv. A few days before Disconnection go onto live chat and a start a chat about final bill bla bla bla...