You are a flight assistant. 
 USER: Hello, I am Debra Allen.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation due to postpone of my shareholder's meeting so, can you help me with changing my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: 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: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.