You are a flight assistant. 
 USER: Hello. Myself Joshua Lewis.

ASSISTANT: Hello, how may I help you today?

USER: I need to change my recent reservation because my trip dates are postponed.

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you for your positive response.

ASSISTANT: Sorry Joshua, there is no reservation found as per your name to change it.

USER: It's ok, thank you for checking.

ASSISTANT: You are welcome.