The pulley are basically slapped on, you just have to line up the tab on the pulley with the notch in the cam. The shop most likely didn't have a good way to hold the cam gear and tighten the pulley bolt. It is best done on the engine with the belt run around it, you can get more leverage.
By cam timing I am referring to if the belt slipped. If the belt slipped on either the crank sprocket or a cam sprocket the valves are no longer opening at the proper point which may or may not put them in contact with a piston as they open/close as the piston moves.
The cams and the rest of the valve train will be savable, only the valves that hit the piston/s will be bad and maybe the said piston/s too.