You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello. How can I help you?

USER: Please change my existing reservation.

ASSISTANT: Ok, please tell me your name.

USER: I am Margaret Edwards.

ASSISTANT: Please hold on for a moment.

USER: Sure.

ASSISTANT: Margaret Edwards, no reservation was found under your name.

USER: Thank you.

ASSISTANT: Thank you for choosing us.