The law states that they must prove that you owe the debt and that they have the legal right to collect it.  You are not required to prove to them that you paid it.  FBCS is well known for violating both State and Federal collection laws.  I can tell you this, they are now required to send this letter out, but I doubt they will:

Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) postmarked within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.

Please also note that if you do send them this letter, they will ignore it and keep calling, which is a good thing, because then you can sue them.

You need to send them a certified, return receipt debt validation letter (think of it as the best $6.47 you ever invested).  Also send it first class mail in case no one will sign for it.  Make a notation of that fact at the bottom of the letter.  You also need to report them to the proper agencies to which I have provided links to.  Then you need to go out and get a consumer lawyer to sue them on a contingency basis (no money out of your pocket) and let them pay you for the harassment.  If everyone did these three things, these crooks would be bankrupt and we would all be the richer for it.  Use these web sites to find an attorney in your state that will probably take the case on a contingency basis (no money out of your pocket up front):  http://www.consumeradvocates.org/
http://www.consumeradvocates.org/find-an-atto ... tates_value=All

Everything else you need to know follows including where to report their criminal activities.

FBCS, INC. AKA FEDERAL BOND COLLECTION SERVICES, INC. AKA FINANCIAL BUSINESS AND CONSUMER SOLUTIONS, INC.
Threads they are mentioned in:
http://800notes.com/Phone.aspx/1-888-581-7449/2
http://800notes.com/Phone.aspx/1-832-516-6512
http://800notes.com/Phone.aspx/1-800-220-2018/3
http://800notes.com/Phone.aspx/1-503-946-5760
http://800notes.com/Phone.aspx/1-267-234-7288
http://800notes.com/Phone.aspx/1-267-234-7117
800notes.com/Phone.aspx/1-615-673-4421
http://800notes.com/Phone.aspx/1-314-480-6954

http://800notes.com/Phone.aspx/1-305-400-0540
http://800notes.com/Phone.aspx/1-405-213-0850
I have to wonder why an allegedly “legitimate “business would need so many phone numbers to call out on?
Web site with contact info in small print at the bottom of the page:  https://www.fbcs-inc.com/?page_id=33

Bizapedia page with companies at that address.  The one company is a Trademark registration company:
http://www.bizapedia.com/addresses/2200-BYBERRY-RD-HATBORO-PA-19040.html
BBB page gives them a B with 65 complaints and 3 negative reviews and an address in Hatboro different from the one previously listed:  http://www.bbb.org/washington-dc-eastern-pa/b ... oro-pa-80015310
Note as of 8/1/16 the BBB has given them no rating and is updating information for them, and has removed all the complaints.
PA Dept. of State lists two other business names for them as well as the owners:
Name    Name Type
Financial Business and Consumer Solutions, Inc.     Current Name
FEDERAL BOND AND COLLECTION SERVICE, INC.     Prior Name
________________________________________
Business Corporation - Domestic - Information
Entity Number:    919627
Status:    Active

Entity Creation Date:    5/5/1986

State of Business.:    PA
Registered Office Address:    330 S Warminster Rd Suite 353
Hatboro PA 19040
Montgomery
Mailing Address:    No Address
________________________________________
Officers
Name:    JOSEPH NEARY JR
Title:    President
Address:    STE 1202200 BYBERRY RD
HATBORO PA 19040-3739
________________________________________
Name:    JOANNE NEARY
Title:    Secretary
Address:    STE 1202200 BYBERRY RD
HATBORO PA 19040-3739
________________________________________
Name:    JOHN P NEARY SR
Title:    Treasurer
Address:    STE 1202200 BYBERRY RD
HATBORO PA 19040-3739
________________________________________
Name:    JOSEPH NEARY JR
Title:    Vice President
Address:    STE 1202200 BYBERRY RD
HATBORO PA 19040-3739
Note that some of the other complaint sites go back as far as 2004, so they have been criminals violating the FDCPA for some time now.
Other complaints:
http://whocallsme.com/Phone-Number.aspx/8885817441
http://www.everycaller.com/phone-number/1-832-460-1810/
http://www.cardreport.com/wwwboard46/messages/31688.html

Read up on your rights here and also make a complaint at this government site:  http://www.consumerfinance.gov/

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:   http://800notes.com/faq/attorney-general

As well as the PA AG’s Office:   https://www.attorneygeneral.gov/Quick_Links/P ... omplaint_Forms/

Please also note that they are associated with this criminal enterprise (a junk debt buyer) called JH PORTFOLIO DEBT EQUITIES, LLC DBA JH CAPITAL GROUP.

The CFPB is well aware of both criminal enterprises.