You are a flight assistant. 
 USER: Hello. I am Gregory Johnson.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation due to postponed of my exams.

ASSISTANT: Ok.

USER: Can you help me with that?

ASSISTANT: Sure, I am perky to help you. Please wait for a while, I will check your reservation.

USER: Sure.

ASSISTANT: Thank you for being patience.

USER: Ok.

ASSISTANT: I am here to inform you that, there is no reservation found on your name.

USER: Ok, No problem. Thanks for the information.

ASSISTANT: Thank you for contacting us.