You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, can you help me out?

ASSISTANT: Sure, I am really happy to help you today in changing the ticket details. Can I know your good name please?

USER: Thank you. I am Margaret Martin.

ASSISTANT: Ok, please give me sometime to check the status of your ticket.

USER: Sure.

ASSISTANT: I regret to inform you that, I could not found any reservation which is under your name in the confirmation list to change the ticket details.

USER: Ok, no issues. Thank you.

ASSISTANT: Most welcome. Thank you for choosing our travel agency.