I have a return guest who attempted to make a reservation with expired card information still listed on his account. Now he can only add a credit cad when he reserves the room. He cannot reserve the room because his first prequest (with expired card info) is holding those dates. I cannot find a way to cancel the request since the reservation is not officially made yet.
I would call Airbnb for help. If the reservation was actually accepted do not cancel the reservation because you will be penalized. Airbnb will have to help this guest with their cc and banking info.