double park behind them so they cant leave, then wait or watch out window for them. I live in an apt complex and ppl constantly parking in my assigned space..this is the only way to deal with it. If you call the manager it takes about an hour before a tow truck comes out and then they hear all the noise of the truck and run out to move it. I like to have the final word when i tell them off and the only way to get that is to double park em in.
Also, do they own or rent. If they rent, call you countys ASSESORS office. They have on file the owners name of every single property in your county. Its public information (name, address, land value and dweling value) Look up the landlords name on google for a phone number, call 411 etc and give the landlord a call. If that doenst work write.
Ive done this before and its Extremely effiective! Stopped parking and loud music issue and dog crappin on my lawn all at once!
Calling law enforcment will do absolutely nothing. When its issues on private property, its the property owner that has to deal with it (they will tell you to go file papers with the court and blah blah blah..) Cops can only ASK them to move their car, they cant make them move it.