Actually, this firm violates FCRA only if you've spotted something amiss on one of your credit reports. (That's the ''reporting'' part of the Act.) You may have meant the FDCPA, which regulates collector behavior.

The knowledge that you have active legal rep for the account should end the call immediately. It's unclear from your story if you had the account discharged or beaten down in a prior suit. I would say you can hose this new collector in court if you've documented the call well.

Anyway, it's possible you've somehow attracted a fake payday loan collector. Shrill threats and the lack of a valid business name would be matching attributes. Your defenses are then reduced to complaint submission to the FTC and attorneys general. The FBI is also taking comments on this category of thug via the Internet Crime Complaint Center:

See discussions for these numbers to see if their stories match yours: 704-200-9909, 559-823-5337, 813-441-0108, 443-451-3816, 496-656-7520
 Jun 22nd, 2011
Received a call from a person claiming to be Rick Douglas. Claims that he is with State Process Service out of Texas and was very aggressive over the phone. Made several statements which were not true. Claims that he was calling in reference to Bank of American when told that the case had been taken care of 10 plus years ago, he stated that he would file a refusal against me. Told him had an attorney who had handled case. When talking with subject he refused to give his license number in the State for Process Service, refused to provide a business location and then hung up. Checked the State of Texas and determined that he is not licensed in the state. Subject is in violation of the Fair Credit Reporting Act. If you have been contacted by this Service file a complaint with your State.
 Jun 22nd, 2011