Will,
There are two pumps, one in the trunk on top of the rear wheel (drivers side) controls the "draw in" of the doors. The other under the passenger rear seat controls the lock/unlock, lumbars, backup rods, vacuum to run HVAC when the engine is not producing any. The remote sends a signal to that, pressure to unlock and vacuum to lock. A brand new "close assist" pump is somewhere under $1000, the lock unlock etc is somewhat less. The close assist is fairly common failure, the lock pump not as often.
The dealer will support their work for a year if they did it, but will not support labor if they did not install it. Your mechanic needs to take it back with proof of purchase to where he got it, for a replacement.
I guess you could contact your local regulation agency, states attorney, etc.
Sometimes the dealer, altho more expensive is worth it in the long run...