You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I need to change my reservation.

ASSISTANT: Sure, I am here to help you. May I know your name?

USER: I am Joseph White.

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

USER: Ok, take your time.

ASSISTANT: Sorry to tell that there is no reservation on your name.

USER: No problem and thanks for the information.

ASSISTANT: Thank you for approaching us.