Dispute over Open space on Ground Floor

I purchased a Floor in an Independent residential property which contain total of 4 floors (Ground + Three), without parking. the ground floor is having two gates on entry, one being Common Passage Gate where there are stairscase, lift and common passage from ground floor till roof in same manner at all floors. Another gate is exclsuively for ground floor where there is an open space first then the bedrooms starts in my floor. Now issue is when i went to my floor after purchasing it, the above floor owners said to me that the Open space is not mine, and is being common and to be used by all 4 floors. but to me sellers has explained that open space is for me only and same mentioned in sale deed too. Also above floors owners said to me that it is common car parking space of one car available to 4 members alternatively whereas building doesnt contain parking at all. as on ground level the floor is constructed without stilt parking. Also above floors having open balcony exactly above my open space and those balcony are owned exclusively by them.above my gate they have grill in same manner. if there has been no balcony above that open space available to above floors then it culd be common area. please correct me.