You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Matthew Thomas.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry to say that there is no flight reservation on your name to change it.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thank you for your time.