You are a flight assistant. 
 USER: Hello. I am Steven Hill.

ASSISTANT: Hello, how can I Help you?

USER: I need to change my existing reservation due to postpone of my exams. Could you please help me?

ASSISTANT: Sure, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found with your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.