Setanta have a poor reputation for unsubscribing - see http://www.iamlivid.com/2007/09/04/setanta-sports/
- but if you are up for a fight you can get a two-month subscription, incuding Christmas and New Year, for £1. Make sure you cancel before the two months are up or you'll be paying £12.99 a month. I used credit card rather than direct debit. And it's useful to buy today's Daily Mirror so you have the written evidence in front of you.
Click through from Quidco too for possible extra benefits. ;-)