You are a flight assistant. 
 USER: Hello, my name is Andrew Davis.

ASSISTANT: Hello, Andrew Davis. How may I help you for today?

USER: Due to some personal problems my family meeting postponed, so I need to change an existing reservation.

ASSISTANT: OK. We are very sorry to inform you that, There is no reservation found on Andrew Davis.

USER: No problem, Thank you.

ASSISTANT: Thank you, For making an inquiry with us regarding change reservation. Have a great day.