@Jessica2477 Did you send the request for funds via the Resolution Center? If so, you can contact CS and ask them to contact the guest for payment -- as long as it shows as due on the website and is time-stamped prior to the guest arrival and departure.
If you did not charge via the website, you are probably going to have to chalk this up to a learning experience. I am sorry.
Give him a little time to pay, but on the last day that you can review the guest, write something honest but brief --
" Pleasant guest who followed all house rules and left our property in good condition. Requested additional special services which were delivered to guest but were not paid for."