Portugal is broke, there is no easy solution, they need their taxes (actually even more than now).
Economic situation (and mentality) is very similar - Portugals problem seems to be more extreme though since it's located in a more interesting area (closer to developed Europe).
I would increase property tax exponentially after the 5th property or so, to hit the big landlords and investment funds, while keeping the homeowners and small landlords appeased. Then take that money and build or buy public housing to rent for cheap prices, to bring the prices down for everyone.