You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, may I know your good name please?

USER: I am William Clark, I want to change my existing reservation as my interview got postponed.

ASSISTANT: Ok, please wait a moment, I will check the status and inform you back.

USER: ok.

ASSISTANT: Sorry to inform that no reservation found with your name to change.

USER: Ok, no issues. Thank you for the information.

ASSISTANT: Thanks for contacting us.