(3)in the case of a stamped paper in which an instrument has been executed by any of the parties thereto, within six months after the date of the instrument or, if it is not dated, within six months after execution thereof by the person by whom it was first or alone executed: Provided that-(a)when the spoiled instrument has been for sufficient reasons sent out of the State the application may be made within six months after it has been received back in the State,(b)when, from unavoidable circumstances, any instrument for which another instrument has been substituted cannot be given up to be cancelled within the aforesaid period, the application may be made within six months after the date of execution of the substituted instrument.
