You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I would like to change my existing reservation, which I have done previously with my name Nicholas Young, can you change it to new dates?

ASSISTANT: Sure, I'll help you with this.

USER: Thank you.

ASSISTANT: Wait a moment please, let me check the database and get back to you.

USER: Sure, get me back with status of my reservation.

ASSISTANT: Nicholas Young, there is no reservation found with your name in our database to change it.

USER: It's ok, not an issue may be it was not done properly while booking itself. Thanks for checking anyway.

ASSISTANT: May be sometimes it happens. Thank you for contacting us.

USER: Welcome.