If there is metal exposed, is it rusted metal? You used to be able to get a rust treatment that you can "paint" on. It turns the affected area black but it does need priming and painting afterwards.
If the spots are dented, filler is the only way and it is horrendous to get into using if you've never used it before. I have only used it on a couple of occasions and I was told that the trick is to put it on in little bits at a time i.e. layer it up VERY slowly - otherwise you end up with too much and a bulge effect and you'll be sanding a small spot forever. You would have to treat the rust, fill the spot with filler GRADUALLY, rub it down, wet and dry to get it smooth, prime it, wet and dry to get the primer smooth and then apply paint which would have to be compounded.
If you were nearer, I would recommend a bodywork place - the bloke is amazing and doesn't charge anywhere near as most places - I think he just enjoys doing the work. Top guy and rather self depricating - I don't think he likes to be told or believe he is as good as he is!!!