You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation. Can you help me in that?

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

USER: Anna Robinson here.

ASSISTANT: Wait a moment please.

USER: Ok.

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

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for choosing us.