You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Please change my existing reservation owing to an emergency.

ASSISTANT: Sure. May I know your name?

USER: My name is Jack Johnson.

ASSISTANT: Please wait a while.

USER: Ok.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Thanks.

ASSISTANT: Thank you for reaching us.