missed call - called back. Disconnected. Scam

Said it was for LED lighting and wanted me to confirm some personal details- when I indicated I was not interested they hung up. Have called every weekday now for almost 3 weeks and always around 4pm. I have seen the number come up each time and have answered them 2x- requested they remove my number from the database- they hung up again. How do these people get away with this when we are on the Do Not Call Register. Painful.