A client in a secured government facility used a custom Paradox application to manage employees, track hours, parts, labor, and generate invoices. The hardware on which the program existed was failing and other contractors had been unable to migrate it to a new system.
The client was required to change the program logic for how it calculated invoices, however the company which developed the application no longer had the developer on staff, no longer had the source code for the "delivered" (binary only) sections, and did not have the administrative password.
Client had been quoted estimates in the high 5 figures for rebuilding the application. Within minutes I was able to identify the OS issues preventing the hardware migration to a new system and withing a week had migrated the application, reverse engineered the necessary "delivered" sections, and pulled the administrative password from the database.
Worked with client through Q/A testing to make sure invoicing and reports were accurate. Client received a working application far quicker than the client thought was possible and at a cost far under budget. Worked with client for several years updating the legacy system while they upgraded.