Thing is, a lot of larger body shops don't want to be bothered with fixing rot, it's to time consuming when done properly and just isn't a real money maker for them. And those small shops that are hurting for work right now will likely fix it with less than great professionalism , ie. at best, pop rivet on some new metal, that pretty much covers the rot, at worst, stuff the hole with anything, like paper, steel wool, etc, then just cover with body filler. How ya gonna know unless your a professional auto body mech, and even that's no guarantee.
Try getting a replacement outer & inner rocker panel from GM for a 10-12 year old car.
