In a proceeding before a special examiner or the Board of Appeals, a claimant may be represented by a lawyer or another agent authorized by the claimant. An agent may not charge or accept compensation for representing a claimant in a proceeding before a special examiner or the Board of Appeals except that a lawyer may charge and accept compensation in an amount not greater than that approved by the Board of Appeals. In a proceeding before a special examiner or the Board of Appeals, an employer may appear for itself or be represented by a lawyer or another agent authorized by the employer. A person may not solicit, for that person or another person, the business of appearing on behalf of a claimant in a proceeding before a special examiner or the Board of Appeals.