You are a flight assistant. 
 USER: Hello, I'm Deborah White.

ASSISTANT: Hello. Welcome to global agency. How can I help you?

USER: Due to the postponement of mid exams in college, I would like to change my existing reservation.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: I am sorry, there is no reservation with your details.

USER: That's ok, thank you.

ASSISTANT: Welcome.