You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you?

USER: I am Katherine Brown. I want to change my existing reservation, due to postpone of my exams.

ASSISTANT: Sure, I will help you.

USER: Can you please help me with that? Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for your time, but no seat is reserved for you in any flight.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for approaching us.