You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you at this moment?

USER: Can you change my reservation details?

ASSISTANT: Sure, I will help you with that.

USER: Thanks.

ASSISTANT: May I know your name for further process?

USER: Myself Donald Miller.

ASSISTANT: Please wait a moment, I will check your reservation status.

USER: Ok.

ASSISTANT: There is no previous reservation available in your name Donald Miller.

USER: That's fine. Thank you.

ASSISTANT: Most welcome.