In a hearing to quash, modify, or terminate the wage assignment order, the court may grant relief only upon a showing that the wage assignment order causes extreme hardship or substantial injustice. Satisfactions by the defendant of all past-due payments subsequent to the issuance of the wage assignment order is not grounds to quash, modify, or terminate the wage assignment order. If a wage assignment order has been in operation for twelve consecutive months and the obligor's payment towards a court-ordered legal financial obligation is current, the court may terminate the order upon motion of the obligor unless the obligee or the department can show good cause as to why the wage assignment order should remain in effect. The department shall notify the employer of any modification or termination of the wage assignment order.