This is not legal advice until: I go to law school, graduate law school, become licensed in your jurisdiction, and confirm your retainer check had cleared.
Talk to a lawyer to determine where they can be sued. If you provided code to them, revoke the license to use/distribute that code and inform them of that. File a copyright on that code. Then sue them for piracy, breach of contract, fraud, promissory estoppel, unjust enrichment, etc. Once you get a judgement, seize assets, have the court find the corporation in contempt, lock up the officers. Have a blue police box wait for a few people who can help. Essentially, go to war.