You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, we are here to help you. May I know your name to proceed furher?

USER: My name is David Wilson.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for your time, sorry no reservation found on your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for opting us.