Builder charging the maintenance without completing the promised amenities.

I purchased a flat in Bangalore. The project has 14 blocks in total and each block has 98 flats in it. Out of 14 blocks only 1 block is construction is completed and OC is received for completed block. 54 flats have been handed over to the owners. But we donot have any amenities except security, DG connection, water, electricity, lift and house keeping. We have not yet received BESCOM electricity meters for individual home, reserved parking facility, children play area, club house, party hall, swimming pool etc which counts to a total of 35 amenities as mentioned by the builder. Builder took upfront maintenance charge for the first year during the purchase and we have completed one year after the purchase. Now the builder started asking us to pay 2.5/sqft + GST as maintenance, which we feel is unreasonable. Hence we asked for the audit report of the upfront maintenance charge they collected from us during the purchase and the justification for fixing 2.5/sqft for future maintenance for which the builder is clearly rejected to answer. Here the questions are, 1. Is the builder liable to show us the audit report of the upfront maintenance they collected from us? 2. Can the builder charge GST on maintenance? (2500 would be the maintenance for 1000sqft sized flat) 3. We owners feel 2.5/sqft is too high at this stage and also unjustified by the builder. But the builder is not ready to negotiate on this price. What should we do in this case? 4. Even though the individual meters are not installed, builder is asking us to divide the electric bill of the common meter installed amongst us. Should we pay this amount?