You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to change my recent reservation, As I have to go for a meeting with another client on same day of journey.

ASSISTANT: Can I have your name to change your ticket?

USER: Joseph Collins here.

ASSISTANT:  Joseph Collins, there is no reservation found under your name to change it. Thanks for contacting us.

USER: It's ok, anyway thanks for your help and information.