In the meantime the state website says this:

If you overpay your premiums, you will see a credit balance on your account. You can use this amount to pay future premiums. If the amount is over $50, you can request a refund by contacting the Customer Care Team at paidleave@esd.wa.gov or (833) 717-2273.

Have you signed into your account to see if the credit is there?