You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you at this moment?

USER: I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Sure, may I know your good name please?

USER: Sure, I am Brian Lewis.

ASSISTANT: Sorry there is no existing reservation found on your name in our records.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.