You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. May I know your name please?

USER: My name is Mark Nelson.

ASSISTANT: Wait a moment please.

USER: Sure.

ASSISTANT: Mark Nelson, we haven't found any reservation under your name in our database.

USER: Thank you.

ASSISTANT: Thank you for choosing us.