(a) No provision of this part shall prevent or interfere with, and no provision contained herein shall be deemed or construed to prevent or interfere with, any agreement between producers and milk cooperative agricultural association or corporation organized under the laws of this state, or a similar association or corporation organized under the laws of this or any other state.
(b) Nothing herein contained shall prevent any milk dealer from contracting for his or her milk with such cooperative agricultural association or corporation.
(c) Dealer payments of over-market premiums made to cooperatives shall be passed through, in whole, to producers for the premium owed to the producer under this part.