You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Rachel Green.

ASSISTANT: How may I aid you today?

USER: Can you please help me by changing my existing reservation? As my meeting got postponed at New York.

ASSISTANT: Sure, please wait a moment.

USER: Sure, I will wait for your information.

ASSISTANT: Thank you for waiting. Sorry Green, there are no active reservations to change the flight.

USER: Ok, not an issue. May be something went wrong while booking the ticket previously. Thank you for providing information.

ASSISTANT: Thank you for reaching our service.