Apartment maintenance charges for housing society in Kerala

Hello, I have an apartment in a 100% residential building in Kerala, possession of which was handed over by the builder a year ago. There is just one building/tower with 32 flats, of which 16 flats are 3bhk (1700+ sqft) and rest 16 are 2bhk (1200 sqft). There are also three (3) , 1bhk flats (600 sqft each). There is np other facilities like club house or swimming pool or solar/heated water etc. During this first year, the builder charged maintenance at Rs. 2.50/- per sqft. Now, the builder is handing over to the residents association and the 3bhk folks have decided that maintenance will be charged flat wise and not sq.ft. wise. What this does is it reduces their maintenance charges substantially while it increases the maintenance charges for 2bhk and more so for 1bhk owners. The 1bhk owners now have to pay more than double of the original maintenance mentioned in the Sale agreement. The 3bhk owners and association secretary/president/chairman have ganged up and are hell bent on making sure that maintenance will be flat wise. This is unfair for the 1bhk owners. These owners do not have parking space either, as per sale deed. A number of 2bhk owners are also against the proposed formula for calculating charges. What would be the right formula to arrive at a fair and just maintenance charges for all owners? also, if this were to take a legal turn i.e. case is filed by the 1bhk and some 2bhk owners, what would be the chances of a favorable ruling for the minority group, in court of law?