If there is a small dent, most cities have some variant of on-the-spot dent remover. Around here their trucks say "Dent Wiz" and they have an 800 phone number. Less common, but growing I think, is a comparable service for when there's no dent but small chips in the paint. I think they are called (cleverly) "Paint Wiz." Much cheaper than allowing a body shop to repaint the entire door to fix one microscopic chip.