There should be links on the community pages, on the listing pages, on every page of the web site, that lead to a page that shows the multiple ways to contact AirBnB.
AirBnB must make it easy to contact them!
Response from Airbnb
Making sure you have the tools to reach Airbnb when you need to is important to us. We’ve just introduced a new feature that will help hosts and guests reach our Customer Experience team during and 48 hours on either side of a trip. We’re also piloting a new way for you to connect quickly with Airbnb beyond just phone and email. Learn more about how we’re making it easier to find our phone number and additional contact information.