Hello @Kama0,
The guest pays Airbnb so all payment issues are for the guest to solve with Airbnb.
There's nothing that the host can do except to suggest that the guest contacts Airbnb.
You could look up the contact information and give the guest the information but you'd have to be firm and point out that that's as involved as you can get as you have no way of knowing the nature of the payment problem.
Contact information for Airbnb con be found by typing "contact airbnb" in the "Search the community" box on the forum pages where you see these questions and answers. Suggestions will appear as you type. Click on the "Contact Airbnb: A Community Help Guide" one.
Steve.