You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation due to prepone of my plans. Can you help me in that?

ASSISTANT: Sure, I am here to help you with your concern.

USER: Thank you.

ASSISTANT: May I know your name please to check your reservation status?

USER: Larry Davis here.

ASSISTANT: Please hold on a moment.

USER: Ok.

ASSISTANT: Larry Davis, no reservation has been found on your name in our records.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.