You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Emma Johnson.

ASSISTANT: Thank you for providing your name.

USER: I want to modify my journey dates in my existing reservation which was reserve to New York.

ASSISTANT: Ok.

USER: Can you help me to change it?

ASSISTANT: Sure, please hold on.

USER: Sure.

ASSISTANT: No reservation found on your name.

USER: Ok, thank you for informing.

ASSISTANT: Thank you for choosing us, have a nice day.