Rotors that are worn down to spec don't get turned, they are replaced. When they installed the new rotors they should NOT have turned them: if they did, this may be one reason they warped so soon. I suspect that they may have used an impact wrench on the lug bolts which then warped the rotors. They should be tightened with a torque wrench in a star pattern to 63ft-lbs, using a small bit of anti-seize on the bolt threads and nut seats. I actually took a permanent marker and, in large letters, noted the torque specs on the inside of each wheel cover on mine in case someone doesn't know that the standard American car torque of 100-120 ft lbs is not appropriate. I just hope they can read..

By the way, Volvos are just different enough that using the local "general services garage" even for items like brakes may be a prescription for trouble. My kids and I just did the front brakes on their Cavalier. The rotor refurbishing, bolt re-torquing, etc. are all different than my Volvos and if I didn't know the difference I would certainly create a problem.