You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Charles Brown here. I was made a reservation earlier in this week. But I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, I will help you.

USER: Ok.

ASSISTANT: There is no reservation on your name in our database.

USER: Anyway, thank you for the information.

ASSISTANT: Thank you for choosing us.