Marc D Wasserman , AAA Collection Agency threaten to ruin credit with scam based on cars that have been sold ANAHEIM California

My son sold a car 12/14 and promptly sent  DMV a release of liability. The buyer apparantly never paid fees to have car transfered into his name. Received letters of demand in 2017 from Southside Tow Service, AAA Credit Service and now Marc Wasserman, a lawyer demanding payment of over $2,000. Threats of court and ruining credit rating. All three companies are refusing to accept the liability release certified by DMV saying transfer was incomplete as if it was our responsibilty to drag in new owner. Big scam. Provide documentatioin and hold your ground. Don't let court threats and lawyers scare you. If you can show DMV record of the sale, you are right and they are conning you. I'll bet they've scammed enough people for a class action suit if someone could get ahold of their files.  They've been doing this for years.