Brakes stickin after brake job

Well, I'm still curious as to where the guy that sold it to him came up with the Mustang crap. That's clearly all Mopar.
I had a friend sell a car to a car shop guy in Richmond VA, and the shop guy turned around to sell it, all the while representing himseldf by name as my friend. He just did not want to re-title the car, so he lied about who he was and signed the papers falsely. There are all sorts of fools and slimeballs out there.

Let's keep in mind that, per the OP, the shop took the info on the Mustang rear from the OP. So they were sorta directed down this path. But they sure show no sense of checking behind the customer for the sake of safety and covering all the bases, and no adequate knowledge of what they are working on.

So to the OP: Are you going to tackle this yourself? (Best solution IMO.) It really IS a fairly straightfoward process and there will be plenty of good advice coming here.