You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Joseph Adams from Los Angeles.

ASSISTANT: Welcome to flight booking agency Joseph. 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 for your positive response.

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

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 reaching to our services, have a great day.