Whenever in the course of reorganization supervening conditions render the plan of reorganization unfair or its execution impractical, the Commissioner may modify the plan (provided the modification is with the written consent of the depositors and other creditors representing at least seventy-five per cent in amount of the total deposits and other liabilities which are impaired or lessened by the modification) or may, provided the Federal Deposit Insurance has not been appointed, appoint a receiver for liquidation as provided in this Act.