You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: Sure, my name is Raymond Allen.

ASSISTANT: How can I help you?

USER: My vacation has been postponed.Can you please help me for changing the existing reservation?

ASSISTANT: Sure, please give me some time.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found by your name.

USER: Ok, It's fine. Thank you for your information.

ASSISTANT: Thank you.