Each contract made by the corporation with any person (other than subscribers), corporation, association and institution, named or referred to in section three of this article shall contain the following provisions:
(a) That the person, corporation, association or institution will render to any subscriber such service as he may be entitled to under the terms and conditions of the contract issued to the subscriber by the corporation;
(b) That the person, corporation, association or institution will accept as full payment for services contracted for subscribers such compensation as is set forth in the contract between such person, corporation, association or institution and the corporation;
(c) That in the event a surplus remains after an annual accounting of the financial condition of the corporation, such surplus may be used by the corporation, upon an affirmative vote of a majority of its board of directors for the following purposes, in the order of priority stated below:
(1) To liquidate on a pro rata basis any obligation due any such person, corporation, association or institution in previous years;
(2) To return the original contributions for working capital, or any part thereof, on a pro rata basis;
(3) To reduce rates charged subscribers, or to expand the services rendered them.