Complex sentence: Art Williams, enraged after discovering some American owners had received discounts and extended payment periods on their franchise fees, threatened litigation and at first refused to honour the balance of Matt Dunigan's sizable contract before the matter was dragged through court.
Split into simpler sentences: Art Williams, meanwhile, became enraged when he discovered some American owners had received discounts and extended payment periods on their franchise fees. He threatened litigation and at first refused to honour the balance of Matt Dunigan's sizable contract before the matter was dragged through court.