Parking spaces have often been a matter of prime concern for several apartment complexes.
According to the “Apartment Act” in most states, car parking is a part of the society’s common areas. Since the purchase of parking slots has been deemed illegal, the transaction to purchase would become null and void. Once the housing society is registered, it becomes the owner of all the common spaces of the apartment complex including the parking spots.
Therefore selling of flat with car parking space separately mentioned in the sale deed is actually illegal and invalid.
However you can sort it out with the association and get a parking space allotted to your flat exclusively.
If nothing happens in your favor you may resort to legal process by first issuing a legal notice and then through court of law.
Consult a local advocate on this immediately and sort it out legally.