I haven't done it for a couple of years, @Thibault106 , but I just took a look in the Help Centre. Down near the bottom is a "Contact Us" button. That will take you through many prompts -- one of them likely loops back to this community centre, but don't choose that. From there you should, with patience, be able to reach someone.
If that doesn't work, I know Twitter does. The account you want to message there is "AirbnbHelp".
Hope that helps. Let us know how it turns out?