General contractor denied payment on two change orders totaling approximately $1 million to J.C. Cannistraro but failed to provide certified rejection as required by Massachusetts prompt-pay law. After arbitration ordered payment, a second arbitrator found the subcontractor had inflated costs and ordered a $600,000 refund, which was challenged. (Source: https://www.enr.com/articles/62482-court-to-general-contractor-too-late-to-reclaim-600k-sub-overpayment)