The department shall cause investigations to be made of complaints received concerning violations of this chapter and shall report the results of such investigations to the attorney general. The attorney general may institute proceedings to enforce the provisions of this chapter. Any manufacturer, distributor, or retailer who violates any provision of this chapter shall be issued a warning by the department for any first violation. Repeat violations shall be subject to a civil penalty of not more than $250. Each violation of this chapter shall constitute a separate offense, and each day that such violation continues shall constitute a separate offense.