You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you for the day?

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

ASSISTANT: Sure, I am gleeful to help you with that. May I know your name please?

USER: Justin Perez.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting.

USER: Ok.

ASSISTANT:  Sorry to say that, there is no active reservation found on your name in our database to change.

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

ASSISTANT: Thank you for reaching us, have a nice day.