You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I help you for today?

USER: My name is Anthony Lee, I want to change an existing reservation.

ASSISTANT: Sure Anthony, please wait a moment meanwhile I'll check the details of your existing reservation.

USER: OK sure.

ASSISTANT: Sorry for the inconvenience, no reservation found on your name.

USER: OK, Thank you for your service.

ASSISTANT: You are welcome. Have a nice day!.