My skybox started playing up back in november.
I rang them up to be told that because I didnt have the insurance I would have to pay for an engineer to come out something like £65 (call out charge) and then pay for the new set top box, something like £100 as I asked for the sky+ box.
I just said to cancel the TV, Internet and phone line as I can join Virgin for less than half the figure they quoted me.
They came to with a supply and fit all in for £80. I said no its ok and hung up. I then rang back 10 minutes later and spoke to someone else. They got it down to £60 all in. I said no thanks I think I will go to Virgin so she came back with £30 all in for the engineer to come and fit the new sky+ box and dish

You just need to haggle with them mate.
They also gave me 12 months warrenty on the new box, lol