You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Larry Green. Due to the postponement of my concert dates, I would like to change my reservation. Will you help me?

ASSISTANT: Sure, I can help you with that. Please allow me a moment to check the details of previous reservation.

USER: Sure.

ASSISTANT: Larry, I see that there is no reservation found under your name.

USER: It's fine. Thank you for your help.

ASSISTANT: You are welcome. Thank you for contacting us.