Where an undertaking given under section 44 is violated, the Director-General may, in compliance with the provisions of this Act, take all necessary steps as may be necessary for the imposition of provisional measures, using the best information available. In such cases, definitive duties may be levied in accordance with this Act on goods imported for consumption not more than a period of three months before the application of such provisional measures, except that any such assessment shall not apply to imports entered before the violation of the undertaking.