I’ve realized that after a user books a listing, there is little he can do to that reservation besides cancelling it.
Let’s say an apartment offers a paid extra called “daily cleaning” for $10$ per day.
You can book the apartment without selecting the daily cleaning. A few days later you realize that you actually want that cleaning. There is no easy way to do this except to send a message to the owner and ask him to arrange it.
Could it be an idea to add a feature to modify bookings after the bookings are made? At least the possibility to add extras after the booking was made.