Upon the filing of an application for the approval of any issue of securities or the making of any loan under the provisions of this chapter, a filing fee in the amount of $25 shall be paid, and upon the approval or validation of any such issue of securities or upon the approval or validation of the making of any such loan, and as a condition precedent to the entry of the order of approval or validation, there shall be paid an additional fee equal to one tenth of one percent of the proposed selling price of the securities and the amount of the loan, subject to credit by the amount of such filing fee, and limited, as to any one issue of securities, whether issued at once or from time to time, and as to any one loan to the amount of $250. A public service company may seek approval in one application of more than one issue of securities and more than one loan. In that event, the filing fee shall be twenty-five dollars, and the additional fees shall be computed as if all the issues and loans were one issue or one loan. A public service company that has paid filing fees and additional fees aggregating $250 on account of the approval of loans from the United States may apply for the approval of further loans from the United States on payment of a filing fee and without payment of additional fees. A filing fee shall in no case be returnable, but additional fees paid in advance of approval shall be returned, in whole or in part, should the application be withdrawn or modified or disapproved in whole or in part.