You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I assist you?

USER: I am Susan Campbell, I want change my existing reaervation. Please help me out.

ASSISTANT: Sure, wait for a moment.

USER: OK.

ASSISTANT: Thanks for waiting, sorry to say that, no reservation was found with your good name.

USER: Ok, no issues.

ASSISTANT: Thank you for reaching us.

USER: Thank you.