You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what can I do for you?

USER: I am Margaret Lopez. I need a help in change in existing reservation, because my schedule is changed with another client.

ASSISTANT: Ok, I will help you to change your existing reservation.

USER: Ok.

ASSISTANT: Please wait for sometime.

USER: Sure.

ASSISTANT: Sorry to say that, we did not find any reservation on your name.

USER: Ok, no problem, Thanks for providing information.

ASSISTANT: Thank you for approaching us.