You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Amy Wilson here.

ASSISTANT: Please, wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting. I am sorry to inform you that, there is no reservation found  on your name.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for approaching us.