Hi,
that's an old problem of that area. A bit more than 20 years ago, me and a few friends went from Lisbon in a car to the Gibraltar area and spent the night in the car, parked at Tarifa beach. Came early morning and we all went for a stroll on the beach. I took only binoculars with me, leaving the scope in the car. A few of my friends did the same. The area was apparently deserted, we saw or heard no one at all anywhere. A few fine Audouin's Gulls later we were back to the car, just half an hour maybe? It was horrifying to see one lateral window had been broken and all our scopes, tripods, cameras and (personally) money were gone. Complete shock as we were aiming for a few days enjoying the raptor migration wonders.
We went straight after to the Tarifa police HQ and filed in a complaint (not sure these are the adequate terms) against uncertain people. They seemed interested but we realized they wouldn't do anything, they weren't going to investigate anything. It adds colour to the description to say they had a typing machine there that 20 years ago was already a museum item, with several missing keys.
Still in shock we decided we'd go back to the crime scene and we'd investigate it ourselves. We were aiming to search for any possible clues, footprints, or even to find suspicious people around there trying to make further victims. Back at the spot I had an idea: to try and think as the robbers: where would I hide a large number of items effectively. There's a stream flowing to the beach which is bordered by dense vegetation, in particular dense rushes. I walked in zigzag going upstream on the right bank of the stream and suddenly, perhaps 1 km upstream (or less), bingo! A small clearing among the rushes full with all our stuff and more... there were documents from many more victims, even car keys. It was hard to believe at the time we had beaten the robbers, just seemed too good to be true (after something that seemed too bad to be real). But of course, my money didn't show up (it would be the equivalent to about 100 euros I think, still before euro). We collected everything and went to Tarifa again to inform the police and to leave with them all item that weren't ours. It felt to us like victory indeed and the police officers just couldn't believe, they seemed baffled. From there we went to a car shop, got our car window fixed and set off to the Gibraltar rock to search for Barbary Partridge (which we found). Raptor migration was disappointing unfortunately, but I got my lifer White-headed Ducks later at Laguna de Medina, so not all was terrible.
So, as you see, this problem goes back at least 20 years. I wonder if they still use the same hiding place... of if the local police has ever investigated anything there now they must have computers instead of that fantastic typing machine...