@Gary740
I would call CS and they can contact the guest on your behalf. CS won't give you their contact info but ask that they tell the guest you would like to refund the pet fee but need them to contact you via the app in order to do so. Once they message you, you can ask them for their Pay Pal info or try again through the Resolution Center.
I would NOT let CS refund it to them on your behalf....I just feel like that's too many hands in the pot and they always seem to mess things up.