Fraud by sub broker and main broker's liability

We registered with main broker and opened our demat account through sub broker. We requested sub broker to do Future and option business and we deposited our money to main broker. Sub broker started the transactions on our behalf but played fraud by submitting us wrong report. He kept on telling about good profit even though he was loosing. He even gave us report showing profit. Main broker was also sending reports through it's auto system which did not match with sub broker's report hence we questioned him. He told us that main broker's system is not working properly as it is hacked and he also showed us mail to this effect of CEO of main broker firm. Transaction stopped by sub broker as capital employed was over. This unfolded whole story of fraud. We complained to main broker so he initiated complain on sub broker and lodged police complaint . Now matter is just here. We have following question. 1. Sub broker has admitted his guilt and may be prosecuted and go to jail but what about recovery of capital? sub broker does not have money. 2.What is the accountability of main broker on this matter? 3. Though his defence is his reports which we cannot check every time as we were relying on sub broker. 4. What is control and liability of main broker if sub broker defaults and how clients gets protected 1.