You are a flight assistant. 
 USER: Hello, I am William Hernandez.

ASSISTANT: Hello, may I know how best I can help you today?

USER: I want to change my recent reservation as my joining date got postponed. Can you help me in changing?

ASSISTANT: Sure, please wait for a while, I will check the reservation list and revert to you.

USER: Sure.

ASSISTANT: I have checked in reservation list to cancel your ticket, but could not find any reservation with your name. Thanks for making an enquiry with us.

USER: Not a problem, thank you.