Any verified complaint filed with the department pursuant to this chapter shall be filed not later than nine months from the date a complete account of sales was due. This period, however, does not include the length of time it takes to secure a written letter of denial from the federal agencies responsible for administering the federal Packers and Stockyards Act, 1921 (7 U.S.C. Sec. 181, et seq.) or the federal Perishable Agricultural Commodities Act, 1930 (7 U.S.C. Sec. 499a et seq.).