You are a flight assistant. 
 USER: Hello.

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

USER: I am Rebecca Smith.

ASSISTANT: Welcome to flight booking agency Rebecca Smith.

USER: Due to sudden work, I need to change my reservation. Can you please help me with it?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please hold on a moment.

USER: Ok.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our records.

USER: Ok, not an issue.

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

USER: Thank you.

ASSISTANT: Welcome.