You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Due to an emergency, I want to change my existing reservation.

ASSISTANT: Ok, may I know your name?

USER: I am Jack Harris.

ASSISTANT: Jack, sorry to say you that there is no reservation found with your name to change.

USER: Its ok, thank you for your information.

ASSISTANT: It's my pleasure.