I bought a BMW of a guy who had used a Brillo pad to try and remove lime scale , there were lots of scratches on the bonnet and bumper, so I got some wet and dry 2000 grade and a bowl of water with detergent in it, then I very gently rubbed down the clear coat wiping it dry every minute, when you have taken it down as far as you can you then t cut the area back to a shine, this will hopefully help, if you have gone right through to the paint you will then need to get some paint and either fill the scratches until it rises above the old paint, let it dry properly then wet and dry it all level, this should work well to a degree, if its that bad then get it prof detailed
Good luck