You are a flight assistant. 
 USER: Hello.

ASSISTANT:  Hello, how can I assist you today?

USER:  I am Brenda Adams want to change my reservation due to prepone of my exams. Can you help me in changing?

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

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:  Thank you for your help.

ASSISTANT: Thank you for choosing us.