You are a flight assistant. 
 USER: Hello. I am Ryan Johnson.

ASSISTANT: Hello, How can I assist you today?

USER: Could you please change my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: 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, thank you for informing me.

ASSISTANT: Thank you for reaching us.