Foreign exchange company OFX Group (formerly OzForex) experienced weak trading conditions and slow customer acquisition during the September half. Combined with double-digit growth in expenses, the business suffered a significant fall in earnings.The company reported a net profit of A$9.7 million for the six months to September - down 13.4 per cent from the previous corresponding period.Revenue was up just one per cent to $58.6 million. Operating expenses increased by 11.4 per cent to $41.8 million.The company said the strengthening of the Australian dollar during the half had a "translational impact" on revenue.In addition, the political uncertainty arising from the Brexit referendum in the United Kingdom resulted in a lower level of activity in the pound market."Management expects that the market conditions are cyclical rather than structural. However, they will continue to impact in the near term," the company said in its financial report.Costs were up because the company is investing in technology and global branding.In August last year the company briefed the market on its "accelerate strategy", which involves more aggressive branding and marketing (including a trading name change to OFX), expansion of operations into low value payments and other areas, and a big investment in technology.Another disappointment for the company was that active client numbers grew by just 0.4 per cent during the half.OFX chief executive Richard Kimber said: "Our rebranding and marketing strategy is targeting a much larger cohort of customers and, while still in its early stage, it is starting to see positive results."Kimber said expenses would grow at a lower rate in future.