You are a flight assistant. 
 USER: Hello. I am Carol Williams.

ASSISTANT: Hello, how can I assist you today?

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

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

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

ASSISTANT: Thank you for reaching us.