I think you've been had, my friend.
A chain and cassette being worn at 1 year? Well you must be up around 6-7000 miles, I would think. Either he's put one of those dreadful 'wear detectors' on it, or he's just plain bulling.
As for two chains. As far as I'm aware, bike shops buy chain on a roll and cut it to length, or they have the correct length in stock or can get it. Again - bull.
There will be no such thing as 'Wisper' parts where brakes are concerned, they will be Shimano or Tektro os some such.
As Nealh says, learn to do it yourself. There's plenty of youtube how to videos and it's much more satisfying and loads cheaper.