@Anita436 I go to the guests if they don't calm down five minutes after 1 text and I don't even think twice about it. It is my house, there are other apartments here and if they don't respect me or more importantly the other guests they are free to go. Interestingly enough, I have found that when you go with the attitude that you don't care if they stay or go but that it is their privilege to stay in a place like yours they always calm down because they know you don't need them but they need you.
@Anita436 Depends on why you feel uncomfortable, is it a personal safety issue? I would go straight over there and tell them what is, if need be take a friend. Your place, your rules, they need to know that in no uncertain terms and the consequences for not abiding by them. Always best to have your own contingency plans - Airbnb customer support will not do anymore than you have already done. Make sure you address all of this via the message board so there is a trail of communication. If any communication was outside the message board make sure your reiterate it on the Airbnb message board.
@Anita436 If you don't feel comfortable going over there, bring a friend or family member (hopefully one who looks like someone you wouldn't want to mess with). I would never rent out an entire home listing if I was reticent to go over and enforce rules that were being ignored, or kick them out if they refused to comply.
Would you feel more comfortable to know the neighbors had to call the police and then try to get your listing shut down?