Try G3 compound and a angle grinder with the modified buffer on the end of it. You can get it from any car body repair agents. Squirt some water and washing up liquid on the scratches then the G3 and start buffing. The angle grinder just works quicker than your elbow so the scratches should disappear. Once the scrathes are out use Mer car polish to go over the area because the paint will be soft and will need to be protected. I had a load of light scatches over mine and this worked a treet.