Betterment fees by Duplex builder

I have purchased a Duplex in Bhubaneswar, Odisha where the land layout is approved by BDA and ORERA. The allotment letter says the total amount of the Duplex (additionally Registration, Holding Tax, GST and other taxes as applicable). As the approved plan layout is for land, there were 2 agreements one for land (45% of the value) and the other for construction of the building (55% of the value). The approval plan for my building was then sought against my name only and I paid the charges as well. Builder had earlier said that apart from any additional construction cost that we do there won't be any extra charges. There is a clause in the construction agreement that any additional construction would be charged extra which he calculated and I have paid as well. However, builder is now demanding Betterment fees in lieu of the drainage system, storm water drain, road, gates, boundary walls and landscaping to the tune of 500/sq. ft. on the construction area which would roughly be ~11 lakh rupees. My Duplex cost alongwith the additional construction is ~72 lakhs (GST, registration and other fees excluded). I know the builder is trying to squeeze whatever extra money from us as the property price in the area has shoot up rapidly but is this justified. He has cleverly put up a clause in our construction agreement that this is excluded in the price "All betterment fees and other similar levies/charges by the Government or Municipality or any other authority related to building". On the face of it the clause seems to be related to government fees but builder is using this clause to demand extra money from all of us. Additionally, in my construction agreement it was writing 18 months as completion date but it's been 3 years now and it seems next month we will receive the handover. Please suggest any options.