You are a flight assistant. 
 USER: Hello.

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

USER: I am William Walker, can you assist how to change my reservation dates?

ASSISTANT: Sure, I will help you with that.

USER: Thanks.

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

USER: Sure.

ASSISTANT: There is no previous reservation found in your name William Walker.

USER: That's fine, thank you.

ASSISTANT: You are welcome.