White smoke from brakes after they were repaired?

We recently took our 2007 VW Jetta to a local garage for a yearly inspection. We were told the rear brakes needed to be replaced because the pads were down to nothing and it was metal on metal. The rotors also needed to be replaced but the dealership who put on the last set of rear brakes three years ago when we bought it did not use the official VW tools for the job which meant the bolts holding the rotors on were stripped. The garage had to weld new bolt heads onto the existing bolts in order to remove them, but they finally got the job done to the tune of $355.00. My husband drove the car yesterday (Saturday; the garage finished the job on Tuesday) and upon returning home was happy to smell that the neighbors were grilling food. Except not so much-there was white smoke issuing forth from one of the rear tires. It seems like they forgot to put on a brake pad but I can`t tell for certain because I have no idea what to look for. HELP!!!

The conservative choice is have the car towed tomorrow to the garage and have them check it out. Should be covered under warranty unless something else failed. Without a lot more info, I would blame a possible re-assembly error rather than missing brake pad. Another possibility is that an unrelated part froze up and causing the smoking.

The smoke may represent a caliper sticking on that wheel, holding the pads against the rotor too long, not that something is missing. I would jack the car up and see if I can hear scraping, both with or without the wheel. Work the brake pedal to see if the wheel/tire assembly stays free after braking. However, it has been a very long time since I have had to replace calipers in any of my cars, including a 1995, so I am not sure my impressions here are correct. If I am correct, it is very possible the pads on that side is glazed and the rotor may now need replacement due to the smoking and heat generated.

Thank you very much for your help-I truly appreciate it!

Another thought is to make sure the parking brake was not on. It could also have been adjusted too tightly, but I would think that it issue would manifest itself on both rear wheels.