Computes the statutory entitlement on a late-paid commercial debt under the Late Payment of Commercial Debts (Interest) Act 1998: statutory interest at 8% above the Bank of England base rate, the fixed-sum compensation under s.5A, and (optionally) reasonable recovery costs. Enter the debt, the date interest began to run (the day after the agreed payment date, or 30 days after the later of delivery/invoice where no date was agreed), and the date to calculate up to.