You are a flight assistant. 
 USER: Hi.

ASSISTANT:  Hello, How exactly I can serve you the best today?

USER: Could you help me to amend my existing reservation?

ASSISTANT:  Let me know your name to check your reservation?

USER: I am Mark Hernandez.

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

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching us.