You might want to re-look through stuff. TCPA laws. And if you have told them not to call, then its on them. Personally I back that up with a certified return receipt letter sent USPS mail. The DNC isn't a call blocker and can not protect you from the illegal callers, extortion scammers, foreign country's and frauds. Criminals do not obey laws simply said.    They use spoofed numbers which make it hard to track them down.. it takes time to do this and many subpoenas for call records.
http://800notes.com/forum/ta-e433d104c45c9b7/ ... oofed-caller-id
http://800notes.com/forum/ta-c3355f57425c0d5/ ... alls-to-the-fcc
http://consumerist.com/2015/07/22/45-attorney ... lock-robocalls/
http://800notes.com/forum/ta-c5c7e69f0670886/ ... -spoofing-calls
http://800notes.com/forum/ta-c46b87360deec56/ ... -unwanted-calls
https://www.ftc.gov/news-events/press-release ... ainst-political

http://www.tcpalaw.com/
https://www.donotcall.gov/
By State DNC lists:
http://800notes.com/res/DoNotCall.aspx

Do a search on call blocking devices and phones.If its a cell phone, there are free call blocking apps out there including trac & straight talk.
http://800notes.com/forum/ta-5d4e343675a5629/call-blocking-devices

Report your callers here, not just to the DNC alone:
Federal:
https://www.ftccomplaintassistant.gov/#&panel1-1
https://consumercomplaints.fcc.gov/hc/en-us
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2

By State DNC lists:
http://800notes.com/res/DoNotCall.aspx

To file complaints on Foreign company's and scams:
• Read up on it here:
http://800notes.com/forum/ta-d20d86fdc3e145c/reporting-international-scams
• https://www.econsumer.gov/#crnt
eConsumer.gov: Report Your Complaint
E-mail: [email protected]

FCC Abandoned Calls Complaint form:
http://www.fcc.gov/cgb/consumerfacts/1088D-R.pdf
email:  [email protected]