In any action taken, proof by the party plaintiff that he has been compelled to discontinue the relationship of manufacturer, agent, dealer or representative on account of the unlawful act or breach of said contract by the party defendant or that the party defendant has threatened to cancel said contract without good cause and without first having submitted the question for an adjustment of a breach of said contract to a board of arbitration and award, shall be conclusive evidence of damage, and in every case proof of any unlawful purpose or agreement to violate the terms of said contract, shall entitle the party injured thereby to all actual damage sustained by him and shall in addition thereto subject the party violating said contract to the penalty provided in Section 63-17-137.