if you can't find or create a wiring diagram then no-one can be sure what the problems are and how they can be resolved.
......................... if you or a competent technical guy (doesn't need to be one of your incompetent electricians) cannot create such a document then, as was suggested earlier, rip it all out and start again .................. or at least disconnect everything, check each wire for continuity so you can identify them at each end, and then re-connect in accordance with a well-designed wiring diagram. There are plenty of books and documents out there (ask Tony Brooks) to help you design a proper wiring system.