You are a flight assistant. 
 USER: Hello,I am Sharon Lopez.

ASSISTANT: Hello, what kind of service are you expecting from us?

USER: Can you please change my existing reservation as the conference which I want to attend got postponed?

ASSISTANT: Sure, wait for a second. I will check in the reservation list and revert to you.

USER: Sure.

ASSISTANT: Sorry to inform you Sharon Lopez, there is no reservation found with your name in our reservation list.

USER: It's ok, not an issue. Thank you for your information.

ASSISTANT: Thanks for your approach.