The simplified claims procedure provided for in this article is available by election of either Petitioner or Respondent on claims which in the aggregate do not exceed $50,000 in one complaint and a final written decision or ruling has been issued by the Public Agency. It is also available by written stipulation of both Parties on claims which in the aggregate exceed $50,000 in one complaint, whether Arbitration is pursued after a final written decision or under the 240 day rule.