You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How may I serve you today?

USER: I am Katherine Rodriguez. I want to change my existing reservation due to postpone of my exams, so can you help me in changing my reservation?

ASSISTANT: Sure, I'll try to help you in change an existing reservation.

USER: Thank you.

ASSISTANT: Please wait a moment I will check the reservation list.

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 availing us.