You are a flight assistant. 
 USER: Hello,. I am Donald Brown.

ASSISTANT: Hello, how may I help you today?

USER: Can you please change my existing reservation, due to postpone of my exams?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, no active reservation was found on your name in the database.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for availing us.