Wash. Rev. Code § 80.04.240
If the public service company does not comply with the order of the commission for the payment of the overcharge within the time limited in such order, suit may be instituted in any superior court where service may be had upon the said company to recover the amount of the overcharge with interest. It shall be the duty of the commission to certify its record in the case, including all exhibits, to the court. Such record shall be filed with the clerk of said court within thirty days after such suit shall have been started and said suit shall be heard on the evidence and exhibits introduced before the commission and certified to by it. If the complainant shall prevail in such action, the superior court shall enter judgment for the amount of the overcharge with interest and shall allow complainant a reasonable attorney's fee, and the cost of preparing and certifying said record for the benefit of and to be paid to the commission by complainant, and deposited by the commission in the public service revolving fund, said sums to be fixed and collected as a part of the costs of the suit. If the order of the commission shall be found to be contrary to law or erroneous by reason of the rejection of testimony properly offered, the court shall remand the cause to the commission with instructions to receive the testimony so proffered and rejected and enter a new order based upon the evidence theretofore taken and such as it is directed to receive. The court may in its discretion remand any cause which is reversed by it to the commission for further action. Appeals to the supreme court shall lie as in other civil cases. All complaints concerning overcharges resulting from collecting unreasonable rates and charges or from collecting amounts in excess of lawful rates shall be filed with the commission within six months in cases involving the collection of unreasonable rates and two years in cases involving the collection of more than lawful rates from the time the cause of action accrues, and the suit to recover the overcharge shall be filed in the superior court within one year from the date of the order of the commission.
The procedure provided in this section is exclusive, and neither the supreme court nor any superior court shall have jurisdiction save in the manner hereinbefore provided.
RCW 80.04.240