You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Gary Mitchell want to change my reservation due to prepone of meeting.

ASSISTANT: Please wait a moment, I will check and get back to you.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation on your name.

USER: Thank you for your response.

ASSISTANT: Thank you so much for choosing us. Have a nice day.