You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: Can you please help me to change my reservation to other dates?

ASSISTANT: May I know your name?

USER: Sure, my name is Charles Hall.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

USER: Not a problem, thank you.

ASSISTANT: Thank you.