You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Andrew King.

ASSISTANT: How may I aid you?

USER: As my meeting got postponed at Dallas, can you please help me in changing my existing reservation to Dallas?

ASSISTANT: Sure, I will help you. Please wait a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Andrew, no reservation has been found on your name in our database.

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

ASSISTANT: Thank you for choosing our service.