I if it took 5 hrs of labor they must have removed every other pulley, the fans, and removed the motor.
My brother had a 1995 Explorer with the 4.0 and although I know it would have been a pain to change the alternator on that, I am sure I could have done it in under 5 hrs.
I think they did the "charge her double-time for being female' trick on her.
Call and get a quote from a couple different shops. Then call the shop that did it for her, get a quote from them (without letting them know who you are or what you are about). If it changes, dry clean in court, or get some sort of restitution from them, like free oil changes for a year.