You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what help can I do for you?

USER: I want to change my existing reservation, because of postpone of my weekend party. Can you please help me in this condition?

ASSISTANT: Ok, may I know your name?

USER: Sure, I'm Joseph Campbell here.

ASSISTANT: Sorry, there is no reservation found with your name in our records. May be, I think on that day you hadn't done your reservation properly.

USER: Ok, fine.

ASSISTANT: Thank you for approaching us.

USER: You are welcome.