Sewage pipeline repairs going to the kitchen

Namaskar! My society sewage pipeline is going under my kitchen from one end to the other.Now as the flooring has sunken after 25years,my question who will bear the repairs cost? It was decided that the society will bear complete pipeline replacement and flooring cost ,unfortunately it was ( maybe purposely)not noted in the AGM minutes of the meeting ,now the Chairman is pointing that it wasn't noted in "Minutes of the AGM"so we( society)can't pay for the repairs. I can't carry out the repairs as it's a major work with 15 flatmembers' toilets connected to it. In such a case,who's legally bound to repair and is there any rule to compensate the flat owner for the mental and physical trauma caused since 12 years after purchase? Thanking you for your valuable time. T.Shailesh , Dombivli