If we're Representative government, why are Republcans angry at Scott Brown, Susan Collins, and Olympia Snowe?

All the polls in the states they represent are against the Ryan plan by overwhelming margins, so if they voted for the plan they would be voting against the wishes of the people who's vote they representing! our Congress is made up of people who's sole job is to bring the peoples of their district or states answer to the legislation proposed on the hill, not to make the decision that their political party thinks is best against their constituents wishes! the fact that Collins and Snowe keep getting re-elected means they are doing the work their states sent them to do, right?