You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I am Karen Nelson. I want to change my existing reservation due to postpone of my exams.

ASSISTANT: Sure, I am here to help you. Please wait.

USER: Sure.

ASSISTANT: Thanks for your time, there is no active reservation found in your name to change.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for reaching us.