You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Owning to an emergency I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, I am here to help you with that, can I know your good name to proceed further?

USER: I am Karen Green.

ASSISTANT:  I am very sorry to inform you that there is no reservation found under your name in our database.

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for choosing us.