I haven't really been in this thread so don't know if it has already been discussed. I am a Sky broadband customer and was looking to get BT sport but didn't really want to switch my broadband. I phoned Sky up yesterday to see if I could haggle them a bit to get it cheaper. Anyway, I didn't need to haggle as they have an offer on if you stick with them... They reduced my line rental by £8.50 a month for the next 18 months for staying with Sky broadband and not switching to BT (I had BT broadband previously and it was crap where I live anyway), so although I am paying £15 a month for BT Sport HD, I have had my Sky bill reduced so it works out I am only paying £6.50 a month for BT Sport, which between my and my old man, £3 a month isn't bad at all. I'd spend more than that in one game if I went to the pub so I'm quite pleased with it.
I asked the girl on the phone what would happen if I cancelled my BT Sport package, and she said that unless I told them, then they would have no way of knowing... so basically, I'll still get the reduction if I cancel BT Sport within the next year, something I might do once the televised fixtures have been released for the new year.