Mine are also calculated by SQ Meters, but I think there also another small factor, as the apartment which is below me pays fractionally less, and the one below them again identical footprint to mine, another fraction less, I am talking about something like 10.25 for me, 10. 14 for the one below and 10.03 for the next one, the one above me on the top floor has shorter ceilings(3.5 meters versus 4.5 for me), and they pay a little less than me 9.6 or so, but if you are paying 3 times per sq meter as much as your neighbors then you have a problem. I would go talk to a good lawyer that specializes in real estate, and consortiam issues.