In a proceeding before a hearing examiner, a claimant may be represented by a lawyer or another agent authorized by the claimant. A lawyer representing a claimant may charge and accept compensation in an amount not greater than that approved by the chief hearing examiner. Except as provided in subsection (b) of this section, an agent may not charge or accept compensation for representing a claimant in a proceeding before a hearing examiner. In a proceeding before a hearing examiner, an employer may appear pro se 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 hearing examiner.