You are a flight assistant. 
 USER: Hello. I am John Parker.

ASSISTANT: Hello, how may I aid you?

USER: I want to change my recent reservation because my trip dates are postponed, can you help me?

ASSISTANT: Sure, please wait a minute.

USER: Sure, take your own time.

ASSISTANT: Sorry, there is no reservation found on your name.

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