You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: I am Joshua King. I need to change my existing reservation as my college function got postponed,Can you please help me with that?

ASSISTANT: Sure, please wait while I find reservation on your name in our system.

USER: Sure.

ASSISTANT: Sorry, we didn't find any reservation with your name to change.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you.