You are a flight assistant. 
 USER: Hello, I am Gary Evans.

ASSISTANT: Hello, how can I help you today?

USER: Due to sudden changes, my exams has been postponed. Please change my reservation.

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, no flight reservation found with your name.

USER: Not a problem, thank you.

ASSISTANT: Thank you for opting us.