* * * In any case in which benefits are awarded to a claimant in whole or in part upon the basis of pay earned in the service of a person or company found by the Board to be an employer as defined in this Act but which denies that it is such an employer, such benefits awarded on such basis shall be paid to such claimant subject to a right of recovery of such benefits. The Board shall thereupon designate one of its officers or employees to receive evidence and to report to the Board on whether such benefits should be repaid. The Board may also designate one of its officers or employees to receive evidence and report to the Board whether or not any person or company is entitled to a refund of contributions or should be required to pay contributions under this Act, regardless of whether or not any claims for benefits will have been filed upon the basis of service in the employ of such person or company, and shall follow such procedure if contributions are assessed and payment is refused or payment is made and a refund claimed upon the basis that such person or company is or will not have been liable for such contributions. In any such case the Board or the person so designated shall, by publication or otherwise, notify all parties properly interested of their right to participate in the proceeding and, if a hearing is to be held, of the time and place of the hearing. At the request of any party properly interested the Board shall provide for a hearing, and may provide for a hearing on its own motion. The Board shall prescribe regulations governing the proceedings provided for in this paragraph and for decisions upon such proceedings.

Final decision of the Board in the cases provided for in the preceding two paragraphs shall be communicated to the claimant and to the other interested parties within fifteen days after it is made. Any properly interested party notified, as hereinabove provided, of his right to participate in the proceedings may obtain a review of any such decision by which he claims to be aggrieved or the determination of any issue therein in the manner provided in subsection (f) of this section with respect to the review of the Board's decisions upon claims for benefits and subject to all provisions of law applicable to the review of such decisions. Subject only to such review, the decision of the Board upon all issues determined in such decision shall be final and conclusive for all purposes and shall conclusively establish all rights and obligations, arising under this Act, of every party notified as hereinabove provided of his right to participate in the proceedings.

Any issue determinable pursuant to this subsection and subsection (f) of this section shall not be determined in any manner other than pursuant to this subsection and subsection (f). (Section 5(c), Railroad Unemployment Insurance Act.)

In any proceeding other than a court proceeding, the rules of evidence prevailing in courts of law or equity shall not be controlling, but a full and complete record shall be kept of all proceedings and testimony, and the Board's final determination, together with its findings of fact and conclusions of law in connection therewith, shall be communicated to the parties within fifteen days after the date of such final determinations.

Any claimant, or any railway labor organization organized in accordance with the provisions of the Railway Labor Act, of which claimant is a member, or any other party aggrieved by a final decision under subsection (c) of this section, may, only after all administrative remedies within the Board will have been availed of and exhausted, obtain a review of any final decision of the Board by filing a petition for review within ninety days after the mailing of notice of such decision to the claimant or other party, or within such further time as the Board may allow, in the United States court of appeals for the circuit in which the claimant or other party resides or will have had his principal place of business or principal executive office, or in the United States Court of Appeals for the Seventh Circuit or in the Court of Appeals for the District of Columbia. * * * (Section 5(f), Railroad Unemployment Insurance Act.)