You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your name?

USER: Sure, my name is Cynthia Clark.

ASSISTANT: Clark, how can I guide you?

USER: I am going to give a presentation on international competition, but due to some sudden changes, I want to change my existing reservation.

ASSISTANT: So sad to hear. Unfortunately, no reservation on your name in our database.

USER: Ok. no problem.

ASSISTANT: Thank you for contacting our service.

USER: Thank you for your information.