You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Sure, I will help you with that. Let me know your name to check your reservation?

USER: Sure, Jeffery Hernandez here.

ASSISTANT: Ok, please wait a moment.

USER: Sure, I will wait for your response.

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: Oh, it's very sad to hear from your side. Anyways, thank you for sharing the information.

ASSISTANT: Thank you for choosing us.