Try another vendor? Or another model? To be blunt if Yamaha hasn't delivered them yet there might be something fishy like a store that hasn't paid their bills to them? A couple years ago I got in a hurry like you are and ended up with an Eastman Euphonium that's been nothing but trouble with the valves. Between our problems and a lot of other problems the music store we bought both through will no longer deal with them and their product. I think that's a telling sign when a music store has had enough!
Stick to the Yamaha, or go with the Getzen or Conns that were suggested below. I guarantee they'll be better than Eastman!