You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I need to change my existing reservation, Can you please help me with 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: Richard Green here.

ASSISTANT: Please hold on a moment.

USER: Sure.

ASSISTANT: Richard Green, no reservation has been found on your name in our database.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.