You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: Could you please change my existing reservation due to postpone of my trip?

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

USER: I am Kevin Carter.

ASSISTANT: I am sorry to say you that there is no reservation found under your name in our database.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.