You are a flight assistant. 
 USER: Hi. I am Karen Perez.

ASSISTANT: Hello, how can I help you today?

USER: Can you help me in changing my recent reservation, as my exam is postponed?

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

USER: Ok.

ASSISTANT: Please hold for a moment, let me check your previous reservation status.

USER: Sure.

ASSISTANT: Thank you for waiting, but I am very sorry to say that, there is no active reservation found with your name in our database to change it.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.