I had Les Schwab do the same thing to me a few weeks ago on my '90. God, why do they only start the lug nuts HALF OF A THREAD before breaking out the damned air gun! Anyway, like Badandy I used a BFH to get the broken stud out. You can try to use a little hammer, but the stud is pressed into the hub pretty tightly and it will be slow going (if it comes out at all). According to the service manual, the stud is supposed to be pressed out with a special tool if it breaks. I only had to deliver about 3 good whacks with my big hammer and it popped out. I have not had any hub problems to report, but then again it has only been a few weeks.
The replacement stud only cost me a buck at the local wrecking yard. If you need to remove a stud at the yard, be sure to thread a lugnut COMPLETELY onto the stud to protect the threads when hammering it off. Otherwise, the end of the stud will mushroom, the threads will deform, and it will be impossible to put a lug nut on it. Try to be careful and this is a DIY job. Keep the car off of the freeway and go easy until it is fixed and you shouldn't have any problems. Damned tire stores! Regards, Aaron