It's a frustrating situation that some of us have experienced. If they are renters, the only person who can get rid of them is the owner, or if you're in an HOA then that group can pursue it. We had a horrible renter in the town home next to us (against our regulations), and it took almost 6 or 7 months to get them out. They had dilapited old trucks parked in our common driveway, used appliances thrown on their patio, threats to neighbors, etc. It was horrible, but several of us got through to the HOA and management company and they finally were forced to move. It took time, but we didn't give up. I did a happy dance when a tow truck finally arrived to tow those blasted trucks away!