Whenever the Commission, upon petition of any public utility, is of the opinion and so finds, after an examination of the reports, annual or otherwise, filed with the Commission by such public utility, together with any other facts or information which the Commission may acquire or receive from an investigation of the books, records or papers, or from an inspection of the property of such public utility, or upon evidence introduced by such public utility, that an emergency exists, and that the public utility has made a preliminary showing of all the elements of § 56-235.2 sufficient to demonstrate a reasonable probability that the increase will be justified upon full investigation and hearing and is of the opinion and so finds that a hearing to determine all of the issues involved in the final determination of the rates or service will require more than ninety days of elapsed time, the Commission may, in case of such emergency, enter a temporary order fixing a temporary schedule of rates, which order shall be forthwith binding upon such utility and its customers; provided, however, that when the Commission orders an increase in the rates or charges of any public utility by means of such temporary order, it shall require such utility to enter into bond in such amount and with such security as the Commission shall approve, payable to the Commonwealth, and conditioned to insure prompt refund by such public utility, to those entitled thereto, of all amounts which such public utility shall collect or receive in excess of such rates and charges as may be finally fixed and determined by the Commission; and provided, further, however, that no such temporary order shall remain in force or effect for a longer period than nine months from its effective date, and a further period not to exceed three months in addition if so ordered by the Commission.