You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you help me?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Yes, I am Brian Hall.

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

USER: Ok, not an problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.