You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my reservation, can you help me?

ASSISTANT: May I know your name?

USER: I am Christopher Lewis.

ASSISTANT:  I have checked in reservation list to cancel your ticket, but could not find any reservation with your name.

USER: No problem, thanks for checking.

ASSISTANT: Thank you.