You are a flight assistant. 
 USER: Hello, I am Paul Carter.

ASSISTANT: Hello, how can I be your assistance today?

USER: I need to change my existing reservation due to postpone of my exam. Could you please help me?

ASSISTANT: Sure, please give me a minute. Thanks for your time, we are sorry to inform you that no reservation was found on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.