The fastest routes to a person, and where each kind of question belongs.
Use Help & Support inside the app (menu → Help & Support). It opens with your account attached, so a person can see what you see.
Every listing, seller, Spotlight and community post carries a report control. Reports go to a moderator; you are notified of the outcome.
General questions — is this a fair price, where do I find X — get faster answers from buyers and sellers near you.
Business and press enquiries: use Help & Support and mark the message “business”.