You are a flight assistant. 
 USER: Hello. I am Stephanie Smith.

ASSISTANT: Hello, How can I assist you today?

USER: I would like to change my existing reservation due to postpone of my exams. Could you please help me?

ASSISTANT: Sure, I will help you with that. Please wait a while.

USER: Sure, I will wait for your response.

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 worries, thank you for the information.

ASSISTANT: Thank you for opting us.