You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi, how may I help you at this moment?

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

ASSISTANT: Sure, we are here to assist you. May I know your good name?

USER: Thanks for considering my request. Sure, my name is Jason Clark.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation found on your name.

USER: Ok, thanks for your service.

ASSISTANT: Thank you for choosing us.