Can society deny to transfer flat on wife name when husband is dead

My father expired some time ago and we are trying to get the flat name transferred to the mother and children. The society says it cannot transfer the share certificate under our names unless we clear all pending maintenance dues. Can they legally refuse to transfer the share certificate? Secondly, we have an issue in the amount of maintenance they are charging us. A flat with a similar area one floor below us is being charged half the maintenance that we are. Society refuses to give us a fair answer to this. From what I understand, area of a flat has no relation to maintenance being charged. Am I right? Its not that we have not been paying the dues, we have being paying the dues as per the original amount before they increased the fees and doubled it. What should we do?