Duped investors of the Green India Private limited, a chit fund firm, staged dharna in front of the CBI office here on Tuesday demanding stringent action against the company’s top officials for cheating hundreds of investors of the State.On Monday, the duped investors and agents of the chit fund company Microfinance limited had gheraoed the Special Investigation Team office of the CBI in the city demanding the company to submit an affidavit before the Supreme Court to refund their money.