You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Rachel Lee.

ASSISTANT: How may I serve you?

USER: I want to change my reservation, can you help me?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Ok.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: That's ok. Thank you for your help.

ASSISTANT: Thank you.