You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Charles Parker here.

ASSISTANT: Please hold on a moment.

USER: Sure, take your time.

ASSISTANT: Charles Parker, no reservation has been found on your name in our records.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for choosing us.