You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am David Roberts.

ASSISTANT: Ok.

USER: I would like to change my existing reservation, my baseball tournament has been postponed. Can you please help me with changing?

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: Ok, not an issue. Thank you for your valuable information.

ASSISTANT: Thank you for choosing us.