Some useful links

For USians only, I'm afraid.

https://www.annualcreditreport.com/cra/index.jsp
https://www.optoutprescreen.com/?rf=t
https://www.donotcall.gov/default.aspx
http://www.dmaconsumers.org/consumerassistance.html

All are legit, and should be effective. (Do not call is very effective, annualcreditreport goes live next week for me; I've just tried the other two, hopefully they will work out OK).