Society maintenance charges are different for different member

Our society have 24 floor and we received OC in parts. so till 14th floor first OC and after that 2nd OC. at the time of flat booking, our builder has asked us to pay provisional maintenance 2k and 3k for 1bhk and 2 bhk respectively for 2 years. now the catch is, recently we got our society transfer/handover. and now society committee (most of the guys are from below 14th floor) is setting up new maintenance charges (which is almost double than what builder set) now they are saying all of the member should pay new maintenance charges. so people who came after their OC, like people from above 14th floor have to pay difference amount of new maintenance and older maintenance which they paid to builder. and those people who came early (till 14 floor) for them committee has decide they will pay full new maintenance fees. but their 2 years already completed so committee will charge older maintenance rate from them till society hand over which i feel unjust for members above 14th floor. my take is If they were permitted to benefit from a 2.5-3 year maintenance period at the builder's rate, it stands to reason that we should not be compelled to pay additional charges until our two-year term is fulfilled. what is your legal opinion on this?