Debt buyer Collection House was hit by a double whammy during the December half, when a significant number of its purchased debt ledger accounts stopped paying their debts and the rising price of PDLs meant the company could not top up its book.Collection House made a net profit of A$8.3 million for the six months December - down 26 per cent from the previous corresponding period.Return on equity fell from 6.8 per cent to 4.8 per cent.The company buys non-performing loans and puts its collections staff onto the job. An important metric for the business is the number of those loans it can convert to active repayment arrangements.Of 296,000 purchased debt ledger accounts with a face value of $1.6 billion, it has 55,000 accounts with a face value of $387 million under repayment arrangements.During the December half collections fell eight per cent, due to "the unfavourable economic environment."At the same time the price of non-performing loan books increased to levels that the company did not consider "financially viable or sustainable in the long term."Put all that together and you have negligible revenue growth, a 12 per cent fall in operating cash flow and a 26 per cent fall in debt ledger purchases.The company's collection services division, which collects debts on a commission basis, made up some of the difference with a 20 per cent increase in revenue.The company said it was moving into government services and expects to have revenue from that business in the June quarter.