Registration (including stamp duty and other charges) at Super built up area,

I had agreement in Jul 2017 for purchase of a flat of 1550 sq. ft. super builtup area, however the carpet area is less than 1000 sq ft. (Not mentioned separately) My flat was registered in Apr 2022 with following lacuna/ my points for harassment by builder is as follows- 1. I had paid charges and duty (@7%) to govt on total SBA I.e. 1550 sq ft whereas the actual carpet area is less than 1000 sq ft. 2. GST was not mentioned on sale agreement, while during registration I was forced to pay 5% GST extra over the total consideration amount of agreement for 1550 sq ft SBA. In my view Actual GST should be 1% as per the actual carpet area only (need clarity) 3. Bank is continuously charging delay penalty @2% of loan amount dues for last 1 year even after registration of flat. 4. Flat is still not handed over to me, and likely to get possession this month. 5. Common area, lift, parking is yet to be developed. 6. If my registration would have done on time, there was a waiver of registration charges by govt to women in Jharkhand till 2020. Registration is on my wife name. 7. There is few observations remaining on development of internal area/ finishing/ fittings and furnishing which is not clearly mentioned in agreement or sale deed. Sir what remedies are there for me. 8. There is huge violation of RERA guidelines by builder made to empower buyers. When I uses any legal terms to builder he threaten to cancel the deed. It is also mentioned that property rate has doubled of the agreement value, for which he behaves as doing some mercy onto me.