You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I am William Green. I am willing to change my trip dates, will you please help me to change?

ASSISTANT: Sure William Green, I am happy to help you with that.

USER: Thank you for accepting my request.

ASSISTANT: Please wait a moment to check your reservation status.

USER: Ok.

ASSISTANT: Sorry William Green, no reservation has found under your name to change.

USER: It's ok, not a problem with that. Anyways thank you for checking.

ASSISTANT: Thank you for choosing us, have a good day.