You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation, because I need to take up a sudden investigation. Can you help me in changing existing reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your good name for further process?

USER: I am Patrick Roberts.

ASSISTANT: Thank you for providing your name, please hold on.

USER: Sure.

ASSISTANT: Thank you for your valuable time.

USER: Ok.

ASSISTANT: I have checked in the reservation list to change your ticket, but could not find any reservation with your name.

USER: Ok, No issues. Thank you for your quick response.

ASSISTANT: Thank you for choosing us, have a nice day.