You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: Please help me in changing my recent reservation.

ASSISTANT: Sure, we are here to help you. I need some basic information to check your ticket details, can you please tell me your full name?

USER: Thank you. Andrew Walker here.

ASSISTANT: Ok, please wait a minute I will get back to you with the present status.

USER: Sure.

ASSISTANT: I am very sorry to inform you that there is no reservation found under your name in our database.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for approaching us.