You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you for  the day?

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

ASSISTANT: Sure, I am here to help you with that reservation change.

USER: Thank you.

ASSISTANT: May I know your name to proceed further?

USER: Sure, I am Sarah Rodriguez from Austin.

ASSISTANT: Sorry to say that, there is no active reservation found with your name in our database to change it.

USER: No issues, thank you.

ASSISTANT: Thank you for reaching us, have a great day.