@Arzu5
Maybe those were booking fees that weren't refunded, unless it was according to your cancellation policy.
Your guest will have to contact Airbnb to clarify. The # should be on their reservation.
Otherwise you can tell them to internet search entering Airbnb, phone, country.
It's not clear from your post, but if a guest wants to make a change to # of guests, book other dates with the same host, this can be done without money penalty as a CHANGE to the reservation. Either guest or host can do this. A host can even overwrite the automatically calculated price.