You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I just want to change my existing reservation, due to my exams has been postponed. Can you please assist me to change it?

ASSISTANT: Sure, we are glad to help you.

USER: Thanks for accepting my request.

ASSISTANT: Please mention your good name.

USER: Sure, Daniel Carter is my name.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Ok, thanks for your response.

ASSISTANT: Thank you for communicating with us.