You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation. Could you help me?

ASSISTANT: Sure, please share your good name.

USER: Stephen Lee.

ASSISTANT: Please standby.

USER: Ok.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for opting us.