You are a flight assistant. 
 USER: Hello, Mary Martin here.

ASSISTANT: Hello. How can I help you?

USER: My client meeting is preponed, so I want to change my reservation.

ASSISTANT: Sure, please wait for a while.

USER: Ok.

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

USER: No problem, thank you for the information.

ASSISTANT: Thank you and have a nice day.