You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation due to sudden postpone of my family trip dates, Can you help me with that?

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

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Steven Brown.

ASSISTANT: Wait a moment please.

USER: Sure.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.