Your first step should be to write a "cease and desist" letter to the debt collector. This letter should detail the offensive behavior and demand that they stop harassing you. As far as other recourse, I believe the law does have strict penalties for debt collectors who use harassing tactics. You should contact your local bar association or look for attorneys in your area who practice in consumer law or debtor's rights law and schedule a consultation.
Contacts with third parties (someone other then you) are controlled by the following statute. FDCPA §804(3) says: A debt collector shall not communicate with a third party more than once unless requested to do so by the third party, or unless the debt collector reasonably believes that the earlier response of the third party was erroneous or incomplete and that the third party now has correct and complete location information.
So it is clear that third party contacts are allowed.
With respect to threats of a lawsuit, collection against wages or even sending the debt to the local District attorney for possible criminal review the FDCPA §807(5) says: A debt collector shall not threaten to take any action that cannot legally be taken or that is not intended to be taken.
With respect to failing to provide the verification of the debt after the contact with the debtor the FDCPA §809(a) says: Within five days after the initial communication with a consumer in connection with the collection of any debt, a debt collector shall, unless the following information is contained in the initial communication or the consumer has paid the debt, send the consumer a written notice … .” (The notice is referred to as the Validation Notice and includes the amount of the debt, name of the creditor, and important information regarding disputes and verification.)
The FDCPA §807(2) says: A debt collector may not use any false, deceptive, or misleading representation or means in connection with the collection of any debt. This includes the false representation of the character, amount, or legal status; or any services rendered or compensation which may be lawfully received by any debt collector for the collection of a debt.
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Disclaimer: This answer does not constitute legal advice. I am admitted in the States of New York, New Jersey and Massachusetts only and make no attempt to opine on matters of law that are not relevant to those three States. This advice is based on general principles of law that may or may not relate to your specific situation. Facts and laws change and these possible changes will affect the advice provided here. Consult an attorney in your locale before you act on any of this advice. You should not rely on this advice alone and nothing in these communications creates an attorney client relationship. The opinions expressed herein are those of the author only and the fact that he has worked as an Assistant District Attorney; State Supreme Court Clerk; Special Assistant United States Attorney (Hawaii); Assistant Cornell University Counsel or Judge Advocate, United States Marine Corps should not be relied upon to assume that these statements reflect the policy of these organizations.
The debt collector can call a third party once to find you. However, the debt collector cannot tell anyone that he is calling to find you for a debt. Get as much information as you can, send a no contact letter to the debt collector, contact a consumer law attorney.
[I am a Virginia-licensed attorney. This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]