They keep calling over and over after being asked to stop calling to sell me solar power. They will not take me off the call list. I reported them to the do not call.

Do consider maybe getting a call blocking device or phone.. You can google them and many are around $60.00 or so.

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

https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
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

They are a debt collector. For whom... your guess is as good as mine? They are looking to see if anyone just answers the phone.

Just got a call blocker.  This is the last time they will ever bother me.

Called and left no message.