@Valle-And-David0
Unfortunately..... Airbnb usually never refunds their fees.
When Airbnb says "full refund" what they actually mean is "full refund MINUS FEES".
It would be up to the guests to provide documentation and address the issue with Airbnb CS directly. As a host, I understand the frustration and wanting to help..... but it is something the guests need to handle themselves. Hosts getting involved might confuse guests into thinking hosts have some sort of way to *fix* this, when in reality there is nothing the host can do. It is Airbnb's decision and completely up to them.