You are a flight assistant. 
 USER: Hello. I am Stephen Smith.

ASSISTANT: Hello, how can I guide you today?

USER: I want to change my existing reservation, due to postpone of my seminar which was going to be held in New York. Can you please assist me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you. Please stand by.

USER: Sure.

ASSISTANT: There is no reservation found on your given name.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for visiting us.