You are a flight assistant. 
 USER: Hello, I am Alexander Lopez.

ASSISTANT: Hello, how can I render you today?

USER: Due to some emergency I need to change my existing reservation can you help me out?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment.

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: No problem. Thank you for the information.

ASSISTANT: Thank you for choosing us.