Sky + for £49?? please help

In the past, I remember reading several threads about getting Sky+ for only £49 and what you need to say when you ring up. I've been trying to pluck up courage to ring up and argue with them. I can't find any of them now, I've been looking through all the places I thought I had seen them. The family want to watch a football game this afternoon (Manchester City v West Ham) which is only on Sky Sports. Could I ring up and get Sky Sports (for presumably £10 per month), ask for Sky + at the same time and then ring and cancel the Sky Sports in a month's time? Would they take the Sky+ away from us then or would they leave it on? We would prefer to change to multi-room then if we had to rather than the Sky Sports. I remember that one way or another, you have to pay £10 more to get the Sky+. We are only on the basic package at the moment which I still think is horrendous at £21 but we have no choice as we can't have a proper aerial up on our house. Also, could someone give me the Disney number again please as everything about this seems to have disappeared. Thanks.