You are a flight assistant. 
 USER: Hello, I am Cynthia Green.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation, could you please help me?

ASSISTANT: Sure. Just wait for a minute, I will check the details and get back to you.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation on your name.

USER: Its ok, thank you for the information.

ASSISTANT: Thanks for contacting us.