Landowner is not ready to pay their share of maintenance

Hello, I have bought a flat in a society where the builder has entered into a joint development agreement with landowners and 40% of the share belong to landowners. builder has recovered amount for maintaining the society for one year. which has come to an end. now society has to take over the maintenance and builder has agreed to pay the maintenance charges for unsold flats at the rates decided by the association of the society. but at the last moment when contracts of maintenance have to be renewed with the various vendors, landowners are denying to pay the maintenance amount of around 50 flats saying that they are yet to sell the flats and they will not be utilizing anything in the society. As far as I understand, landowners have to pay the maintenance whether their flats are sold or remain unsold. Need expert opinion on how to make them pay their share of maintenance and legal options available if they are not willing to pay. please quote sections or rules if possible. Thanks in advance for any responses.