Brakes stickin after brake job
First idea I had was a different shop.
If they didn't do anything with the fronts then I would think contaminated fluid in the calipers and pitted pistons binding in thier bores.
In a car of this age they shouldn't have touched it at all unless they did a full system with at the very least flushing all the lines.
One other thought would be that the wrong master could have been used and it isn't letting the fluid return to the reservoir when you let the brakes off. (thereby keeping the brakes on.)
Whatever it was/is it ruined the new brakes and your rotors, and they should replace it all.
They should also pay to have your car towed back in since they made it undrivable.
This is what happens when we let people in shops work on our cars.