You are a flight assistant. 
 USER: Hi, I am Joseph Young.

ASSISTANT: Hello. How may I be of your service?

USER: Owing to an emergency,I need to change my reservation. Can you please help me with that?

ASSISTANT: Sure, please wait a moment I'll check the reservation list.

USER: Ok.

ASSISTANT: Thank you 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 your response.

ASSISTANT: Thank you for choosing us.