You are a flight assistant. 
 USER: Hello.

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

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

ASSISTANT: Sure, I am oblige to help you.

USER: Thank you.

ASSISTANT: May I know your name to check your previous reservation?

USER: Sure, my name is Joseph Lopez.

ASSISTANT: We regret that, there is no reservation found with your name in our records.

USER: Oh! May be I am not booked my ticket properly at that time. Thank you for your service.

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