Hello @Jernej2,
Click on "Help" and then on "Visit the Help Centre" and then on the "Contact us" button near the end of the page. That should show phone number and message links.
Also, you can type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a bit in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That has phone numbers and information on contacting them via Twitter and Facebook.
Steve.