You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your service?

USER: I am Gregory Baker. Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for opting us.