(1) Under authority delegated by the provisions in 81-23-104, MCA, the following transactions of business among licensees under the Act and among licensees and the general public are declared to be unfair trade practices subject to enforcement sanctions provided by statute:
(a) The payment of a lesser price than the applicable producer price established by the board pursuant to the Act by any distributor to any producer for milk which is distributed to any person, including agencies of the federal, state or local government.
(b) The payment, allowance, or acceptance of secret rebates, secret refunds, or unearned discounts by a person, whether in the form of money or otherwise.
(c) The giving of milk, cream, dairy products, services, or articles of any kind, except to bona fide charities, for the purpose of securing or retaining the fluid milk or fluid cream business of a customer.
(d) The extension to certain customers of special prices or services not available to all customers who purchase milk of like quantity under like terms and conditions.
(2) This rule and the rescission herein of any previously existing rule does not affect any act or thing done or begun, liability incurred, or any right accrued or established or any penalty incurred or any such prosecution or proceeding, civil or criminal, pending or instituted under or on account of any such previous rule herein rescinded in whole or in part, to enforce any right or penalty or to punish any offense under the authority of any such previously existing rule, at the time this rule takes effect, but as to all such acts, things, liabilities, rights, penalties, prosecutions or proceedings and any such previously existing rule remain in full force and effect.