You definitely need shims on the right rear. I would order 4 so you have a couple extra. It will probably take two.
But you need to shift some of the alignment washers on the front to even out the caster. Depending on what is in your car now would determine what side to adjust on the front. You can't add or remove the front washers, you just change their location on each side of the upper control arm mounts (where it bolts to the frame). That shifts the upper ball joint forward or back to change the caster.
Neither one of those jobs is easy, so you they will probably want to charge more. The front is the worst, which is probably why they didn't adjust it. The maximum difference side to side for the front is .2 degrees. You are at .5 degrees.