If, indeed, you had written and signed a check without funds FOUR years ago, guess what?  You would have gotten a letter from your bank (at least, many of them notify you of NSF checks) AND you also would have gotten a letter from the vendor you wrote the check to, so you could put it right.  You can read more info here about this type of scam:

http://800notes.com/forum/ta-86217073a9c8dad/ ... 077595690349410
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http://www.consumer.ftc.gov/articles/0258-fake-debt-collectors
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http://www.deadiversion.usdoj.gov/pubs/pressreleases/extortion_scam.htm
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Also read up on the laws and your rights:

http://800notes.com/arts/Jb8EW-eDhQA/harassin ... ou-need-to-know
http://www.ftc.gov/os/statutes/fdcpajump.shtm
http://www.consumerfinance.gov/askcfpb/search ...
http://www.consumer.ftc.gov/articles/pdf-0096-fair-credit-reporting-act.pdf

For Extortion Scam Operations,  file reports with the FBI, your state attorney general and Department Of Justice,FTC & FCC..

http://www.ic3.gov/default.aspx
http://www.fbi.gov/
https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
http://www.consumerfinance.gov/complaint/

You may wish to invest in a call blocker also, either device or phone..
http://www.amazon.com/s/ref=nb_sb_noss?url=se ... s=call+blockers