kiteboy dave said..
I have had 2 cars oversprayed with white line marking or idiots using paint guns outdoors.
Clay bar is the answer, maguires etc.
Claybar is probably the first place I'd start as well. I'd avoid megiuars stuff though. Dodo do a good bar as do autoglym. I use autoglym clay bars and dodo juice slippery lubricant. Make sure you use the lubricant. Doesnt quiet work the same way when its dry eh

carcareproducts.com.au has a few options but could try repco / autopro. Get onto it asap.