It depends on the politics of your building. If her parking space has so many boxes that she can’t park in it, presumably her car is in a visitor space whenever she’s home. Are there only three lots? If so, to whom does your neighbour complain about visitor parking? Can’t that authority (the manager? the committee?) speak firmly to her about her own parking?
As for the chicken wire, do you mean a cage that protects your car? Otherwise, there doesn’t seem to be much point in it.
What happens to the boxes if there’s a flood in the shared garage? It’s presumably under the building.