You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I would like to change my existing reservation, which is done recently. Can you please help me out/.

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

USER: Sure, myself Benjamin Campbell.

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

USER: Not an issue, anyway thank you for the information.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your service.