Parking allotment

Sir while purchasing a flat in Ahmedabad builder promise to give allotted parking and same was written in brochure. After registration of Flat he allotted the basement and ground floor foyer parking to 170 flats and leaving 36 flats.  They have been allotted the parking by the side of boundary wall which is illegal and restrict the vehicle for ingress and  egress  movement. Sir please guide what to do and whom to approach if RERA the any RERA expert advocate please.