P.S. In reply to your question - there are many real estate management businesses which are conducted by strictly observant Jews. The business is either closed on Shabbos and Yom Tov, or transferred through a shtar mechirah ("Bill of Sale") duly executed by an orthodox Rabbi. In the latter case only a non-Jew is present at the business premises during Shabbos and Yom Tov. You should consult an orthodox Rabbi in your vicinity and he will explain the matter to you in detail.