Really need help about a stubbornly leaking roof

I wonder if anybody has anything to say about it - ot better yet, recommend a good specialist in the Nashville area. A home owner here has been experiencing a leak, seemingly from the roof, which proved itself impossible to fix ot to diagnose. Repair people have been around the house several times, mostly painted over the damage, only to have more leaking and water damage a few weeks later. The roof has presumably been patched. They typically act rather strange, for instance refusing to recognize any water damage at all. The ruined wall area is growing; recently the curtain rod has fallen out of the wall at some distance from the original leak site. There has to be something different about this particular leak. There has to be a reason why several teams were unable (or unwilling?) to do anything about it. The home owner has spent a lot of money on it. It feels like the house is falling apart and we are helpless. Please let me hear some opinions, we are getting desperate.