You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

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

ASSISTANT: Sure, can I have your good  name to check  your reservation status?

USER: Sandra White.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry Sandra White, no reservation has found under your name to change.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for choosing us.