You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Elizabeth Moore from San Francisco.

ASSISTANT: What service that you are looking from our agency?

USER: 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, I am glad to help you with that.

USER: Thank you for accepting my request.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok.

ASSISTANT: We regret to inform you that, there is no reservation on your name in our records.

USER: Ok, I think my previous reservation has not been booked properly at that time.

ASSISTANT: Thank you for reaching us, have a great day.

USER: Thank you for your information.

ASSISTANT: Welcome.