Legal notice to company

hello sir, i want to send legal notice to a company .......working of that company is getting money from people in the form of investment and in return transfer interest and also making chain so that many people will join and in every joining people will get commission in return. Now after some time company stop making payment and its looks like a fraud company .now they have started return back to people but after deducting amount . i want to send him a notice to return my money and also return money which joined company on my behalf. sir what section is applicable with this company.