You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, may I know your name for checking?

USER: Sure, I am Virginia Walker.

ASSISTANT: Give me a minute.

USER: Sure.

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

USER: Not a problem, thank you.

ASSISTANT: Thank you for opting us.