Unfair maintenance calculation

Hi, I am a owner of a 2 bhk flat in a gated community apartment in Miyapur, Hyderabad. Our Association is planning to charge maintenance not based on sqft but fixed or fixed + sqft basis. The registered by laws of the Association says the below: "25. 'Rules' means rules framed under the Andhra Pradesh Apartments (Promotion of Construction and Ownership) Act 1987 (Act No. XXIX of 1987)." The Andhra Pradesh Apartments (Promotion of Construction and Ownership) Act 1987 (Act No. XXIX of 1987) says the below : "Section 13 Common profits and expenses-The common profits of the property shall be distributed among and the common expenses shall be charged to, the apartment owners according to their percentage of undivided interest in the common areas and facilities." Now the question is when the by-laws say that we are following AP Apartments Act 1987 and the act says the expenses should be based on area, can the maintenance be charged based on fixed/fixed+sqft and not on sqft basis legally