Find a new mechanic. If you continually take it in and they continually don't or cannot fix it, find someone who can. You might also want to look into learning how to fix your bike yourself, but that's a longer term project.
I don't know anything about your model bike, but I assume it should work since it's not a WalMart bike. Fuji makes some nice bike (my first racing bike was a red Fuji waaaaay back in the 80s).