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. The man at the desk said that was rusty water coming out from behind the inner fender. That made me feel really good because it was the same on both sides. If water can get out it can also get in.
When my son took the car back, the man at the desk said that there were no holes, that the seams were welded and that they would charge extra if he wanted more done. I took the car back with my son and they agreed to fix up the problems. The "fix" was to put caulking in the rust hole and to drive the inner fender panel back so that it touched the rocker panel and then applied "seam sealer" aka caulking, to close the seams to water.
What an amateurish hack job.
The guy at the desk said that he was happy with the repair and that he was confident it would last the one year warranty period and that he was not confident the way it had been. So why was the car allowed out of the shop if he was not happy with the half assed repair? Are they out of their minds?
He said they normally cover the inside of the fender well with a tar like material but there was no such material applied when we picked up the car the first time. I guess they figured that a young guy like my son would accept any sort of shit they gave him. The tar also covers up whatever they did so you can't see it anymore. Nice work guys.
If you want your car fixed properly, this is not the place to go. They over charge and they will take shortcuts if they think you don't know the difference. If you take your car back, they will not do a satisfactory fix. They are out to screw their customers. So stay away.