The general manager of Century 21 Prestige said the Florida Keys’ second-largest real estate company by volume filed for Chapter 11 bankruptcy protection to reorganize its debts. Prestige, which has six offices in the Middle and Lower Keys, will keep operating. General manager Dave Lunsford said Prestige’s offices have lost money for years. The company recently struck a deal to return three Upper Keys offices to George Nyman, the original owner. Lunsford said Prestige employs 62 agents and 18 salaried employees in Monroe County.