73. Fees are fair and reasonable if they are justified by circumstances and are in proportion to the services rendered. Chiropractors or the partnership or joint-stock company within which they carry on their professional activities must, in particular, take into account the following factors to determine their fees:(1) the time devoted to the performance of the professional service;
(2) the complexity and scope of the service; and
(3) the performance of services that are unusual or require exceptional competence or celerity.