You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to change my existing reservation, please help me out.

ASSISTANT: Sure, may I know your name please to check the status?

USER: Sure, my name is William Mitchell.

ASSISTANT: William, there is no reservation found with your details.

USER: Its ok, thank you for the information.

ASSISTANT: Thank you for contacting us.