don't get your hopes up of them stopping, unfortunately i was in the same situation two years ago, then last year as well. some people are just rude, disrespectful, and downright unbelievable when it comes to seasonal money.
If I was you, do what I did, have your actors screenshot any crap they see, email it to you privately, and send all the bullshit to your attorney. Then have your attorney write up something small, a letter or even an email through their website (cause you know they're reading those!) and simply have the notice state your intent to make things serious if they don't start respecting your actors and your haunts name.
If that doesn't work. Hit them with every slander and libel lawsuit you can until they keel over and die. I'm sorry to say that, as I'm just about the last person to sue anybody and for the most part I really hate people who are sue happy, but sometimes in this business an attorney is the only way to get your point across. It seems like you have genuinely tried to make things right with them. The sign....well that wouldn't be a bad idea at this point anymore, but check with zoning, they might have something else to say about it.
Good Luck and Continue to take the high road, don't let other people ruin your values or change you as a person. Avoid your actors getting involved at all costs and just let them be there own worst enemy.