You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you out?

USER: Can you help me to change my reservation?

ASSISTANT: Sure, we are happy to help you. Can you please let me know your good name to proceed further?

USER: I am Katherine Green.

ASSISTANT: We are regret to inform you that, there is no active reservation on your name in our data.

USER: No problem, thank you for the checking.

ASSISTANT: Thank you for choosing us.