Think about getting a call blocking device or phone.

As per Tamianth:

Report your callers here, not just to the DNC alone:

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

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

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