You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT: Sure, I am here to help you out with that. May I know your name to check your reservation status?

USER: Jonathan Clark.

ASSISTANT: Ok, please give me a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our records.

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

ASSISTANT: Thank you for approaching us.