They call you telling you were selected, that you're top priority and have high chances of getting the green card (TOTAL LIES AS THE GREEN CARD IS A LOTTERY PROCESS). THEY URGE YOU TO PAY A HUGE AMOUNT OF MONEY, if you show signs of resistance they will tell threat you saying you will have your application blocked and be impeded to apply again for the next two years. THEY MIX some true and fake information to confuse you and push you to pay. THERE'S A SENSE OF URGENCY. DON'T PROVIDE YOUR BANK DETAILS. DON'T FALL PREY OF THEM.
THE GREEN CARD LOTTERY IS TOTALLY FREE IN THE GOVERNMENT WEBSITE.