You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: Due to sudden change in the dates of summit which was going to be held in the place, I want to do some changes in my existing reservation, can you please help me?

ASSISTANT: Sure, can I know your name?

USER: I am Thomas Moore.

ASSISTANT: I'm sorry Thomas, there are no reservations with your name.

USER: Ok, thank you for providing your information.

ASSISTANT: Thank you, have a good day.

USER: Thank you.