You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Daniel Smith.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for opting us.