Builder denying possession to buyer due to his dispute with Land Owner

We have purchased flats from Land Owner, who has signed a Joint Development Agreement with Developer. In JDA it is mentioned that both will share 50-50 flats and cost of constructing flats for tenants will be paid by Owner. Now there is dispute between landlord and Developer on the amount to be paid by Owner to Developer for the construction of Tenants accommodation. Due to which Developer is not handing over the keys of Owners share of flats which we have purchased (OC is received and Developer has given possession to his buyers). We also have taken Home Loans from Various banks. Developer is claiming Lien on Owners property until owner doesn't pay him. However in JDA it is mentioned that Owner can sell 75% of his share to enable him to pay the Developer the cost of tenants flat construction. Our flats are among that 75% share of Owner. Also banks have scrutinized the JDA and sanctioned loans to us. Now what is the remedy with us?