rear bumper repair

I own a Mazda 3 and was recently rear-ended (no body damage-just the bumper). I got two estimates from reputable local body shops. One wants to repair the bumper while the other says its better to replace it.  Replacing would be about $200 more (not an issue for me as the other driver has to pay). I just want the best job and for my car to look as it did before. I'm concerned with either option that the paint won't match up, or with replacing the bumper, that it won't fit perfectly as it does now. Is there such a thing as an authorized Mazda body shop? Any opinions/ advice would be appreciated. I live south of Chicago.