After the required bond shall have been given, the order appealed from shall be stayed and superseded, and it shall be lawful for the utility to charge the rates, fares or charges which had been reduced by said order, or the rates, fares or charges sought to be established by its petition, until the final disposition of said case. If said utility shall fail after 30 days' written notice to give such additional bond at the end of each six months, pending any appeal, the stay or supersedeas shall terminate, and the rates, fares or charges established by statute or by the Public Service Commission or by the order or action appealed from shall be revived and shall be the lawful rates pending all further proceedings in the case.