You are a flight assistant. 
 USER: Hello, I am Joshua Perez.

ASSISTANT: Hello, how can I render you today?

USER: Due to changes in my exam dates I need to change my existing reservation can you help me changing my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

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: No problem. Thank you for the information.

ASSISTANT: Thank you for opting us.