Guests don't follow agreed check-out time and bring 1 person more than booked

Dear all, For the first time we made a rather bad experience with guests. They booked for 3 people and it was 4 people in the end. Guest comment: I could not change my booking to 4 people. Check-out time agreed 11am. Guest comment at 1pm: I thought you would wait for me in the apartment. We had breakfast on the beach. Our rating so far: 9.4

How to handle such experience and to avoid bad rating if we ask for addtional payment. Thanks for sharing feedback and giving guidance.

Kind regards, Ahmed