You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you now?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I am here to help you. May I know your good name to check your reservation status?

USER: John Allen here.

ASSISTANT: Ok, please wait for a moment. I will check with it and get back to you.

USER: Ok.

ASSISTANT: Sorry to inform you that, we have not found any active reservation on your name in our database.

USER: No problem, thank you.

ASSISTANT: Thank you for opting us.