According to ALLDATADIY.COM. the TCM replacement is 1.4 hours (I guess the mechanic had a hard time finding out where the module was located) and the programming is 1/2 hour. I have no idea what your dealerships hourly rate is but a couple of hours for assessing the problem (I doubt it should take more than an hour) plus say 2 hours does not come out to $1600. I'm sure I don't know the entire story, but that's what I see from what has been presented.
Call JOhn Kennedy of Kennedy Sales Co, in Loyal WI. H can provide tested, programmed TCM's to you in the mail. All you have to do when you recieve his is to disconnect your batteries, pull your old TCM, Install the Kennedy TCM, reconnect your batteries. Ready to drive. All this assumes that your TCM is actually the problem. It probably is, but you never know.