You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you today?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: OK.

ASSISTANT: Thank you for your time, we are sorry to inform you that we did not find any reservation on your name in our database.

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

ASSISTANT: Thank you for reaching us.