Maintenance Rate for apartment

We are the Association members of “Anthea Apartment Owner’s Association, Nolambur, Chennai -95 Total no flat is our association is 26 , out which all the apartment are varies with different sqft like 1175, 1200, 1155, 1700, 1600, 1400, 1300, 2400, & 2650 sqft . Initially When builder had quoted during construction it was 2 rs/Sqft. But During hand over the apartment to individual they had proposed for flat rate wherein favoring of few apartments on higher sqft, since there no association was formed, they had continue the same to see for 1 yr. Once the association was formed in year 2017 same was continued, since most of the association member are with higher sqft . only few had quote for changing the maintenance in sqft rate but not positive since there was no quorum. Once when new association members where formed in end of 2017 they had insist in proposal for changing the Maintenance in Sqft since more burden lies in less sqft residents. As they had also informed all the residence that this is as per TNOA act , wherein all maintenance charge are collect based on the UDS. Due to this there was a depletion in few of resident wherein they don’t want to change the current maintenance rate. Due to this they had form a small community of 4 within the resident to address this issue. further they had come up with solution on maintenance can be collect as per slab (i.e. they had frame 3 slab by grouping the apartment) Wherein this is also favoring all the residents at higher sqft .So few resident had taken a decision to given a letter to president stating that they will only pay maintenance in Sqft as per builder quoted during construction but president is forcing the resident to pay on current rate, For the same we need your valuable advise 1. Whether resident can give a letter and silently pay maintenance as per sqft agreed initially and whether this is against the rule of bylaw 2. Whether president / secretory / treasurer have right threatened the resident / force the resident to pay maintenance in flat rate. 3. Whether individual resident can legal this issue to the association