Wow. What an effing nightmare. The police here ARE exactly as you describe them. Absolutely useless. I don't live in La Plata, but the few times I had to deal with them (my garage was broken into a few years ago and the robber took my motorcycle, and a few years later my car was stolen, parked in front of my apartment) they just took my statement and I never heard from them again. No matter who I spoke to, they are always "doing everything possible" which is, of course, absolutely nothing.