You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What help that you need form my end?

USER: Please help me in changing my existing reservation.

ASSISTANT: Sure, I am glad to help you and can I know your name for checking purpose?

USER: I am Jacob Perez.

ASSISTANT: Thank you for your information, 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.

ASSISTANT: You are most welcome and thank you for reaching us.