You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Karen Green. I am planning to change an existing reservation, due to some urgent work. Can you please change my reservation?

ASSISTANT: Yes, I can help you with that. Sorry to inform you that there is no reservation found on your name.

USER: That's fine.

ASSISTANT: Thank you for consulting us.

USER: Thank you for your information.