You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, may I know your name?

USER: I am Ronald Lewis.

ASSISTANT: Wait a minute.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found on your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.