Apartment constructed by deviating from approved plan from GDA, Ghaziabad

I purchased a 3BHK flat recently in Niti Khand – 1, Indirapuram, Ghaziabad, UP – 201014. The apartment was built in around 320 sqm area. Builder taken approval from GDA (Ghaziabad Development Authority) to construct it for residential purpose in the form Ground + 4 floors. The entire ground floor will be reserved for parking the vehicles (it also called Stilt parking). However, builder constructed the apartment by completely deviating from the approved plan. The deviations are as follows 1) Builder has approval to build only one residence unit per floor. However, builder constructed 4 units per floor (total 16 flats were constructed). 2) The entire stilt parking should be reserved for car parking. However, in the one fourth of the stilt parking area, builder constructed a shop and planning to sell it. Because of the shop space in the stilt parking, residents are facing difficulty in parking vehicles. To this end, residents filed a complaint in GDA to remove the shop space. Based on the request, GDA demolished the shop in the last month. From that time, builder started threatening the residents by saying the entire apartment was built illegally and the entire apartment will be demolished by GDA if he provoke. Further, by brining Goons, builder installed iron sheets in place of the shop space. Now, I need the legal opinion/suggestions from the prominent advocates in the area of Real estate from Ghaziabad that 1. Did the build reserve rights on stilt parking? 2. What is the course of action to be taken by residents to retain the stilt parking? 3. Will the GDA demolish the entire apartment since it was constructed against the approved plan? 4. What should be the proactive action to be taken by the residents to retain stilt parking and their flats? 5. Are there any penalization/regularization methods available to avoid demolition?