You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you for today?

USER: I want to change my existing reservation, because of my postpone of my exam.

ASSISTANT: Ok, may I know your name  please?

USER: I'm Emma Mitchell here.

ASSISTANT: Sorry for the inconvenience, there is no reservation found on your name.

USER: Ok, no problem.

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

USER: Thank you for your kind information.

ASSISTANT: You are welcome.