You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: Melissa Phillips here. I want to change my existing reservation, can you please help me in this intent?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Ok.

ASSISTANT: Thanks for your patience. But I am sorry to say that there is no reservation on your name.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you.