You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I amend you?

USER: I want to change my existing reservation due to some personal issue.

ASSISTANT: Sure, I will help you with that. May I know your good name please?

USER: My name is Margaret Hall.

ASSISTANT: Ok, Thanks for your name. Please wait a while.

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: OK,not an issue. Thank you for responding.

ASSISTANT: Thank you for opting us, Have a great day.