Car parking

I am leaving in an apartment over 18years. 1. There are totally 12 flats in this society 2. Apartment has not registered with society and there is no society formed yet. 3. As per agreement, for car parking it is mentioned as ample car parking space 4. While occupying my apartment, the society / maintenance incharge, who is one of the owner in that apartment complex, mentioned in order to live with peace and harmony within the apartment complex, the car parking space was occupied based on first come serve basis 4. There are 12 car parking space available for each occupants, the total occupants are 12. Out of this 12 car parking, 4 were parallel parking and 2 are parallel parking, meaning 6 car parking doesn't have any car behind them. 5. The slot which has 4 parallel car parking are suffering over 18 years since its a parallel parking 5. The 6 occupants who occupied the front car parking and claims that it is exclusive for them since the seller/builder himself marked the car parking space and alloted to them and hence they bought the flat. They don't have anything in writing given by the builder /seller So please advice whether the claim by that 6 occupants are valid or is there any solution