You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: I am Stephen Allen.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for opting us.