They use caulking to repair rust holes. We took my son's car to Aylmer Collision to rust damaged rocker panels replaced. Cost $850 plus tax. They replaced the rusted panels alright. But they didn't repair a hole in the edge of the inner fender, so they left a hole that would let salt water into the cavity. The new rocker panels would not have lasted a year. On top of that, none of the seams where the rocker panel met the inner fender were welded. The "repaired" area was rusting before we even picked up the car... read full review »