In the past nine months Panache Lingerie has doubled its turnover and won back a major contract - both of which, it says, have been made possible by the company's investment in a scaleable computer solution.   Panache designs, manufactures and distributes of a full range of quality co-ordinates for the lingerie industry, with customers including Debenhams, John Lewis, Allders and Matalan. Exports to 32 countries around the world account for 60 per cent of its revenues.