Interesting advice, but in my case I don't think I can usefully dispute it – there are actual functional problems (one rear light cluster was shattered, which is easily fixable, and also the boot was bent so far out of shape that the rear wiper no longer meets the rear windscreen) and also they said the chassis was bent. I certainly wouldn't be confident that I could get it repaired to MOT standard, though I can see how if it was just one dented side panel it might be a different story.