This is most likely Chaplain Financial Services.   See:  https://reportscam.com/chaplain-financial-services/#31874  This 404-400-7603 number is mentioned on that site.

https://www.cfservicesllc.com/
Chaplain Financial Services
CFServices LLC
3577 Chamblee Tucker Road
Suite A #282
Atlanta, GA 30341
phone - 678-609-4847
**
BBB:
(678) 609-4847
Chaplain Financial Services
3577 Chamblee Tucker Road Suite A282
Atlanta, GA 30341
WEBSITE
BBB File Opened: 05/08/2017
Business Category
Financial Services
THIS BUSINESS IS NOT BBB ACCREDITED
Chaplain Financial Services
F BBB Rating System
______________________________
Just because someone on the phone calling you says you owe a debt does not mean you actually owe it.

If a voice on the telephone claims you owe a debt:

1.    Demand the person give you his or her name, company name, and address
2.     Demand a debt validation letter by US mail.  E-mail no good.
3.    Do not pay  the collection agent or anyone else a  dime until the debt is validated

Of course they won’t do this, no scammer ever will, so simply ignore them and block their calls.

If they are bothering you, report them:

http://www.consumer.ftc.gov/articles/0149-debt-collection (Threatening civil proceedings with no intent to follow through, or threatening criminal process in order to collect a civil debt is a  violation of the Federal Fair Debt Collection Practices Act.)  The same goes for endless telephone harassment

Note that the US Supreme Court in the Case of HENSON ET AL. v. SANTANDER CONSUMER USA INC., has recently ruled that the provisions of the Federal Fair Debt Collection Practices Act do not apply if the creditor owns the debt in question.  As a practical matter this probably won't effect the kinds of scam debt collectors who often show up on 800notes.  The scam collectors don't give you any information about themselves so it is impossible to know whether or not they in fact "own" the debt in question.  Most do not send debt validation letters and many often say they are collecting for someone else.  So, make the complaint anyway if they are bothering you.  Let the FTC sort it out.

Also contact your local attorney general

If they continue to bother you,  and you know you do not owe any money, tell them that you know this is  a debt scam and that you are making a complaint to the police for extortion.  Once you get a copy of the police report and they call you again , just read out the  file number and the name of the PD or Sheriff’s office involved.   Tell them you’ll be glad to send a copy to them at whatever address the jack***es are working out of now.

You'll probably have to yell at them and talk over them.  Tell 'em  no scammy debt collector is going to push you around.

You have to get tuff with these people because,  being akin to thugs, brute force is (metaphorically speaking).   the only thing they understand.