You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my reservation due to postponed of my exam, so please help me.

ASSISTANT: Sure, can I know your name please?

USER: Sure, I am Joshua White.

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

USER: No issues, thank you.

ASSISTANT: Thank you for approaching us.