①If the obligation to pay installments under an installment sales agreement for a Building Lot or building for which a Real Estate Broker is the seller is not performed, the Real Estate Broker is to provide a written demand for payment to be made within a prescribed reasonable period of time of no less than thirty days and may not cancel the agreement on grounds that the payment of an installment is late or demand payment of an installment that is not yet due unless said obligation is not performed within said period.

②Any special provision that contravenes a provision of the preceding paragraph is hereby invalidated.