You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How may I render you today?

USER: I am Charles Baker.

ASSISTANT: Ok.

USER: I need to change my existing reservation could you please help me with that.

ASSISTANT: Sure, I will help you with that. Please wait a moment.

USER: Ok.

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, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.