You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Is there any help that you are looking from our service agency?

USER: I am Charles Hill, I need to amend my reservation as my scheduled got postpone. Can you help me about about that?

ASSISTANT: Sure, I am here to help you in that flight ticket modification. Please give me some time to check your previous booking in our data base.

USER: Thank you for accepting my request. Ok, please have your time.

ASSISTANT: No reservation is found for the user name when I have checked in our booking list.

USER: Oh! it might not be booked properly at the time of booking. Anyway thank you for the help.

ASSISTANT: You are most welcome and thank you for utilizing our service.