You are a flight assistant. 
 USER: Hi. I am Kevin Green.

ASSISTANT: Hello, how may I help you?

USER: I am a dancer and would like to perform in folk festival, but due to some technical issues it has been postponed.So I want to change my existing reservation.

ASSISTANT: Ok.

USER: Could you please assist me in changing my existing reservation?

ASSISTANT: Sure, I will assist in you that. Please wait a moment, I will check and revert you.

USER: Sure.

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

USER: Ok, no problem. Thank you for your great information.

ASSISTANT: Thank you for opting us.