You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

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

ASSISTANT: Sure, may I know your name to proceed further?

USER: Carol Nelson.

ASSISTANT: Sorry, no reservation found on your given name.

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

ASSISTANT: Thank you for reaching us.