Stop harassing calls

I am getting 7-8 calls a day from a KNOWN number. If I block the number, they leave voicemails of their TV running in the background.  I tried the free scam shield, which does absolutely nothing. When I asked Tmobile for help, they told me I had to pay the extra five a month. Is there anything one can do without having to pay additional fees? Can you go to the police or something?

Thanks all!