You are a flight assistant. 
 USER: Hello,. I need your help for changing my existing reservation.

ASSISTANT: Hello,. May I know your name please?

USER: My name is Barbara carten.

ASSISTANT: Ok, please wait for a moment, I will check the availability of reservation on your name.

USER: I want to book for new flight ticket.

ASSISTANT: There is no reservation on your name.

USER: OK thank you for your help.

ASSISTANT: Thank you for reaching us.