You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Is there any help that you are expecting from my side?

USER: I have to modify my travelling details in the past ticket because the planned trip got postponed. So, can you please help me to change the ticket details?

ASSISTANT: Sure, I am glad to help you in that flight ticket modification.

USER: Thank you for accepting my request.

ASSISTANT: May I know your name for checking your previous flight ticket booking in our list?

USER: Sure, my name is Gregory Hill.

ASSISTANT: Thank you for your information.

USER: It's ok.

ASSISTANT: I have checked based on your request and there is no reservation found for user name in our previous booking list to help you in ticket modification.

USER: Oh! I have expected a positive response from your end. Anyways thank you for your valuable time.

ASSISTANT: You are most welcome and thank you for reaching us, have a great day.

USER: You are most welcome.