Adjusting fixed pistol sights isn't difficult and does not require the services of a gunsmith. There are two ways to do it that will not mar the pistol. You can purchase a sight adjusting tool with a worm gear that pushes the sight in the direction you need to move it. This is a nice tool to have, but if adjusting you sight is a one time thing, the money is better spent elsewhere.
The other option is to acquire a brass punch that is approximately the same size as the side of the rear sight and use a hammer to tap the rear sight over. A common 16 oz carpenter's hammer is more than sufficient, but if you have a 12 oz ball-peen hammer so much the better. Put a small wedge of wood under the top edge of the slide prior to making the adjustment. This will prevent the gun from rocking when you tap the sight. You make the adjustment to the rear sight and you might be surprised with how sharp a wrap you have to make to get it to move. But don't wind up and belt it, because it will probably move too far then you'll have to bring it back from the opposite side. If possible, make your sight adjustments on the range so you can check your progress on a target.
If the gun is shooting left, you want to move the rear sight to the right. When you aim, this causes you to move the front sight to the right to center it in the rear notch, and your group will print to the right of where it did.