You're in a tough situation. Putting out the flyers probably was a good idea, but it looks like one of the neighbors didn't get the message...
The very concept of having nearby neighbors sucks in general, especially if they can hear what's going on in your house. There are 75,000 square meters of land per family in this world - that's 13.5 football fields! (And world population will start declining a few decades from now, and then there's seasteading, etc.) Surely a well-off first world individual ought to be able to find a place to live without a lot of neighbors nearby...