You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I serve you today?

USER: Can you help me in changing my recent reservation, as my exam is postponed?

ASSISTANT: Sure, I'll try to change an existing reservation. Can I have your name please?

USER: I am Larry Evans.

ASSISTANT: Ok, 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: That's ok, thank you.

ASSISTANT: Thank you for approaching us.