High number of daily calls, though I am on National Do Not Call List

I have been receiving numerous calls, from GE Home Security, every day (including weekends), for over two months.  I am on the National Do Not Call List and have informed every service representative that has called me from this company, of this fact.  I have also asked them to remove me from their call list.  Nothing matters.  They call approximately six times, per day, at all hours of the day.