You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Donna Harris.

ASSISTANT: How may I assist you at this moment?

USER: I want to change my travel dates in my previous reservation, can you please help me with that?

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

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok.

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

USER: Oh! It's ok no problem. Thank you for your information.

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