I have two areas on my car that have been flaked down to bare metal. The picture below is of the rear door area, and the flaked area is right there where the bottom rear corner of the door is. If you open the door, and follow that corner straight in it is in the metal area of that corner. What happens is in the winter, snow builds up in that opening below the door and turns to ice. I think someone kicked that ice and popped the paint off down to metal. A couple months ago I sanded it to remove any surface rust, cleaned it up and rattle canned a couple coats of primer and like three coats of paint. But I just noticed a couple days ago that one side has already flaked off again. We've had snow, so I'm not sure if ice was the culprit, or just bad prep. Any ideas on how to fix this properly?