Upon discovery that an employer is in violation of MGL c. 152, § 25A, the DIA shall issue a Stop Work Order (SWO) and serve it upon the employer. Service of the SWO is proper if it is served upon the employer personally, if the employer is an individual; upon a corporate officer, if the employer is a corporation; or upon a representative or agent of the employer. The SWO may also be properly served by leaving a copy of the SWO at the employers' last and usual place of business. The date of service shall be noted on the SWO and said date shall be used to calculate fines and penalties pursuant to MGL c. 152, § 25C.