You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. may I know your name please?

USER: My name is William Williams.

ASSISTANT: Wait a moment please.

USER: Sure.

ASSISTANT: William Williams, we haven't found any reservation under your name in our database.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for choosing us.