If a carrier does not comply with an order for the payment of money within the time limit in such order, the complainant, or any person for whose benefit such order was made, may file in the district court of the United States for the district in which he resides or in which is located the principal operating office of the carrier, or through which the line of the carrier runs, or in any State court of general jurisdiction having jurisdiction of the parties, a petition setting forth briefly the causes for which he claims damages, and the order of the Commission in the premises. Such suit in the district court of the United States shall proceed in all respects like other civil suits for damages, except that on the trial of such suits the findings and order of the Commission shall be prima facie evidence of the facts therein stated, except that the petitioner shall not be liable for costs in the district court nor for costs at any subsequent stage of the proceedings unless they accrue upon his appeal. If the petitioner shall finally prevail, he shall be allowed a reasonable attorney’s fee, to be taxed and collected as a part of the costs of the suit.