You are a flight assistant. 
 USER: Hello.

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

USER: I want to change my reservation, due to some problems I am unable travel those dates so can you please change my reservation?

ASSISTANT: Sure, I am oblige to help you. Can you please provide your name to check your previous reservation?

USER: Thank you, my name is Paul Evans.

ASSISTANT: Please hold on to check.

USER: Ok.

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

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

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