Best to have a quiet chat with the guy and tell him that you've had a nightmare because there was a load of overspray on your car and you had a nightmare cleaning it off.Tell him that if their going to spray could they ask you first so you can make sure your cars out of the way.tell him that the cars important too you and not some shed you just use for work.explain that there's a few people muttering about what he's up to but all you care about is your car so a little respect would be great.still no joy?take photos,tell them your car keeps getting damaged,tell them you've seen them using spray cans in a public area that affect the ENVIRONMENT,say you've heard them use abusive language,seen them clocking cars etc.the more shit that gets piled on them the more the council will go down and act.business rates?they should be paying them so mention that as well if you think there not!!!!