I did the same thing. the first time i told them to stop f'ing calling me. he said stop f'ing or stop calling? Like really!?!? UGH well they are on my block list so when they call my phone never rings.
They have been harrassing me for almost a year now. I have Verizon and I can block up to 5 numbers at a time for free. Even so, after a few days, they call from a different number. I wish I knew how to stop them. Unfortunately, you can pretty much call from any number now and not worry about it getting traced back. I suspect this will go on indefinitely.