You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Shirley Wright here.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.