You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Myself Sharon Jones from Houston. I want to do some changes in the existing reservation because my friends are not able to come on the those dates, can you please help me?

ASSISTANT: Sure, please hold on for a moment, let me check.

USER: Ok, thank you.

ASSISTANT: I am sorry, there are no reservations with your name.

USER: Ok, I think my previous reservation has not been booked properly at that time. Thank you for your service.

ASSISTANT: Thank you, have a good day.