I hope that you can get the bike back. If you are having a hard time with the shop where you bought the bike, you might try taking the bike to a different shop and tell them about the flats. Tell then that you would like to try adhesive backed rim strips and a puncture resistant set of tires and I'm sure that they will be able to help you. I know that you'll probably have to go a long way to get to another bike shop but you didn't have anything to do this weekend anyway, did you ?