You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I need to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure, can I know your name please?

USER: Karen Baker here.

ASSISTANT: Ok, wait a moment please.

USER: Ok.

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

USER: Ok, not an issue.

ASSISTANT: Thank you for approaching us.

USER: Thank you.