You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

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

ASSISTANT: Sure, May I know your name?

USER: Samantha Johnson here.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.