You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I am David Taylor, can you assist me how to change my reservation dates?

ASSISTANT: Sure, I will help you with that.

USER: Thanks.

ASSISTANT: Please give me a moment, I will check your previous reservation status.

USER: Sure.

ASSISTANT: There is no previous reservation available in your name David Taylor.

USER: That's fine. Thank you.

ASSISTANT: You are welcome.