What do I do?

If the experience was really that bad. I would check around to see if another bike shop has or can get the same bike in. If they can't then I would give them a second try, especially if the Bike Fit is right. Components can be changed and upgraded the Fit is Key.

Tell a shop that you'd like to work with your dilemma. See if they can configure an "equivalent" bike for the same price. Tell them you're looking for a bike shop you can build a relationship with. Tell that to the store manager/owner etc. and not the mechanic, although something the mechanic is the owner!

To me, I'd still get it and go elsewhere for service and fit. It's pretty hard to find the perfect bike and setup. But without knowing your experience with the shop, it's hard to say. I'd definitely check into their experience with handling warranty issues...