N.Y. Public Service Law § 88

§ 88. Defense in case of excessive charges for steam heat. If it be\nalleged and established in an action brought in any court for the\ncollection of any charge for steam for heat or power, that a price has\nbeen demanded in excess of that fixed by the commission or by statute in\nthe municipality wherein the action arose, no recovery shall be had\ntherein, but the fact that such excessive charges have been made shall\nbe a complete defense to such action.\n