You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I oblige you today?

USER: My name is Donna Jones.

ASSISTANT: Ok.

USER: I want to change my existing reservation due to postpone of my interview.

ASSISTANT: Sure, I will help you with that. 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: Not an issue, thank you.

ASSISTANT: Thank you for choosing us.