You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I am Paul Brown. I want to change my reservation, can you help me?

ASSISTANT: Sure, I am here to help you out. Paul Brown, we regret to inform you that there is no reservation found on your name in our records.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for choosing us.