You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Justin Smith. As my interview in Detroit has been postponed.

ASSISTANT: Sure. Please wait for a while.

USER: Help me in changing my existing reservation.

ASSISTANT: Ok. We have not found any flight reservation on your given name.

USER: No problem, thank you for your response.

ASSISTANT: Thanks for choosing us.