Can car parking and water sump registered to one flat owner?

I bought a flat in 2007. As per the approved layout, a car parking of area 16 x 40 is shown. Recently, one of the flat owner is saying that part of of the car parking area (8 x 40) is registered to him and hence he is not allowing others to use that area. Also, the water sump for all flats is located in the 8 x 40 area that he claims is registered to him. So, he is not allowing others to use the water sump as well. Details about the property: There are a total of 7 flats. 6 of the flats were sold out between 2007 to 2010. The 7th flat was sold some time later. The first 6 flat owners (including me) believed that the car parking of area 16 x 40 is common to all 7 flats and we can share it based on rotational basis. But, recently the 7th flat owner has started creating nuisance by not allowing us to park in half of the area and not alowing us to use the water sump as well. Can anyone advise if it is legal to register part of the car parking and the water sump area to one flat owner? What action can be taken from other flat owners to make the car parking and water sump as common? We are afraid that if we file a case, it might take years to get resolved.