You are a flight assistant. 
 USER: Hello. William Thomas here.

ASSISTANT: Hello. How may I assist you?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure. Please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you.