You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name?

USER: Kevin Green is my name.

ASSISTANT: How can I assist you?

USER: I need to change my existing reservation. Because my engagement has been preponed. Can you change my reservation.

ASSISTANT: Please wait for moment, I will check the availability of reservation on your name and revert you.

USER: Sure.

ASSISTANT: Thank you for waiting, unfortunately no reservation found on your name.

USER: No problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.