You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, may I know your name to check your reservation from our data base?

USER: My name is Larry Jackson.

ASSISTANT: We regret to inform you that there is no active reservation found on your name to change.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for opting us.