A. I would like to suggest that the terms and conditons fo the Joint Developmetn Agreement which was executed between Owner and Developer should be verified in respect of Commercial complex. You need to verify your Sale Deed or Agreement of Sale read with Construction Agreement's terms and conditions towards the commercial complex portion area. As per the General rule of law, the builder cannot hold UDS of the flat buyers what the land utitlized to built residential complex.
C. Check the Plan approval, land survey sketch to identify your land and as well land conversion as to how much land has been converted for residential and commercial and check total land avilabiltiy for the residential and also commercial. If the builder clearly mentioned the Sale or any deed towards the flat buyer as to how much area available for the residential and your flat UDS had been calculated as per the said area in accordance with the plan approval then you cannot recover the same. However, you can recover the same by approaching court if the builder obtained whole plan approval for construct residential unit and if he had built against the plan approval and land conversion. As per your query, if the concerned authority permitted to contruct commercial alongwith residential and if the flat buyer had been agreed under the agreement that you cannot recover the same.