You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: My name is Brian Anderson. I want to change my existing reservation.

ASSISTANT: Sure, Brian Anderson. Can you provide your details?

USER: I would like to change my reservation from DC-DCA to CO-DEN.

ASSISTANT: Sorry, We didn't have any reservation on your name.

USER: OK.

ASSISTANT: Thank you for contacting us.