Car parking sell able or not

Dear Sir/Madam, i Hv purchased a 1BHK flat in Navimumbai, our building is a 06 story building having two lifts & 48 Flats, total 15 car parking, My point is weather the parking slot is sellable or not, as i have gone through many web sites which states that the builder cannot sell a stilt/ open car parking to any one, as almost all the parkings are sold to the residents. Now builder is pressurizing us to park my car outside building premises as i have not purchased the car parking. Kindly guide n help me what step should i take.