us grant department

I have been getting call from this number for about 8 months, they told me that I was randomly selected to receive a $7000 grant, I refused to give them any personal information without further confirmation and they would hang up. The next month I would get another call. Last month when I refused and told the person to take me off their list and stop calling me, the cussed me out calling me insulting names and hung up. I want the to stop calling and I feel I should warn others.