Does your call blocker have area code blocking? If so, block it by the area code. The newer call blockers do have some area code blocking abilities. If you have it, this usually solves the use of them calling from same number sets and easier then blocking them individually.  So, if it really is Conns calling, then simply send them a C&D letter via USPS certified return receipt mail telling them to stop calling your number. Most company's usually do not get the picture until its sent in writing.

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

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

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

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

Conns' alternates between trying to collect on a paid in full account or increasing our credit limit. They evidently still use a file card system to run their accounts receivables or the monkeys have not found the correct keys yet. If you deal with Conns, get everything in writing and make sure you have written proof from corporate that they did not make a mistake. They are trying to charge me for loan insurance for over a year on an account I paid off early. Corporate gave the pay-off to the store manager and now say they were not asked for the insurance pay-off. I was supposed to keep paying the insurance for a paid out account.