Shoddy business practices have been discussed on this site for at least the 20 years I've been on here. Everyone has an opinion, and it's always difficult to determine who is serious, who is venting, and who is clearly kidding.
Vigilante justice is only good advice if you wouldn't mind being incarcerated yourself. There is no quicker way to exchange your status as victim to that of perpetrator. Want to make a bad situation worse? Easy, commit assault and battery on the con man, and now he's the victim.
Lawyers always cost money in these situations, as no qualified attorney would take a case like this on a contingency basis, since a lucrative award that could be split with an attorney is unlikely. The victim may be awarded restitution in a negotiated settlement, but a sizable damages award in very unlikely. See below.
Since the business is in California, the county District Attorney would be the law enforcement person to contact. Each state handles civil/criminal complaints differently, and, in California, you don't contact the Attorney General, which is a state office. You contact the county DA in one of Cailfornia's 58 counties
Los Angeles County District Attorney's Office will have an online website that likely has consumer complaint forms the public can download, complete, and forward to the DA's Office. Victims photocopy all relevant documents, emails, and any other writings that support their position. The Consumer Fraud attorneys have the option of filing a civil or criminal complaint, but usually file civilly, since the victim is more concerned with money damages than jail time for the perpetrator. In addition, the elements of criminal fraud are more difficult to prove than unlawful business practices.
All of us who have been wronged at one time or another may fantasize about revenge, but there really is no easy way to get satisfaction. Crooks know this and use it to their advantage. That's how they stay in business for such a long time. Whatever route you choose, don't put yourself in legal jeopardy just to get revenge. We ARE the good guys, and we've worked too long and hard to throw it away.