Non payment of maintenance to builder

Hi, Our property has still not been handed over by the builder and hence he continues to charge maintenance fees which includes property tax. Few members have stopped paying maintenance to Builder on account of service deficiency while others have continued to pay him. Now we are in the process of forming a provisional committee and taking handover from the builder. Will it be the builders responsibility to collect his dues from the non-paying members or can he offset that against the payment made by other members and handover the account to the society? In that case, the members who had been paying diligently stand to lose since they have already paid to the builder as well as have to pay to the society. Whereas the defaulters who are in majority & in all probability be office bearers, stand to gain as they will be paying only when the society gets formed. Any advice? Since builders maintenance included property tax, doesn’t it mean that the defaulters did not pay property tax also?