You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I am Kevin Collins, I want to change my reservation as my plan to visit friend is postponed. Can you help me with that?

ASSISTANT: Sure, please wait for couple of minutes.

USER: Sure.

ASSISTANT: Thanks for waiting, but no reservation is existed with your name.

USER: Ok, thank you for the information.

ASSISTANT: Thank you.