Centering the steering wheel is part of an alignment.
You may have more going on here though. Since the caster and camber are not adjustable by ordinary means unless you have installed the caster / camber plates, an alignemnt will not solve a pulling problem. You can adjust the toe until the cows come home and it will not change a pulling problem.
I suspect that you have a tire problem. They tried to rotate the tires to solve the pulling problem. A tire pull is sometimes manifested by an off center steering wheel.
If you got a read out from the alignment (and you should have), please post the readings and I may be able to help.
When you have a steering pull, one common way of determing if it is caused by a tire, is to swap the two front wheels. If it is a tire pull, it will either go away or start pulling the other direction. Even if you have unidirectional tires, it is safe to swap sides long enough to road test for the pull. It usually pulls in the direction that the bad tire is located on. When a tire that is causing a pull is on the front, it can sometimes also cause the steering wheel to go off center. The steering wheel can be straight on the alignment rack but be off center when driving.
Sometimes a tire that is causing a pull will restore itself from running on the rear for a while, so once you have determined which tire is causing the pull, put it on the back for about 5,000 miles or so.
All of this gets really nasty when you have more than one tire causing a pull. Sometimes you have to find a like car with known good tires and swap all tires and wheels for a road test to prove that the alignemnt is proper.
If the tires are all good and you have a slight pull, sometimes you can make a small but perhaps enough change in the caster / camber readings by shifting the subframe, but don't mess with this until you know that the tires are good and you can see from the alignment readings that this could help. Basically, you loosen the subframe bolts while on the alignment rack and pry the subframe so that you push one wheel slighty forward or the other one slightly back or both.
If you truly do need to make any real significant change in caster or camber, you need to install the caster / camber kits.
Post the alignment readings.
