Not getting flat possession due to dispute between landlord builder

Booked a flat, builder is not giving possession of flat due to dispute between him and landlord, due to failed agreement between them, now landlord says he wont start new agreement with builder and will make the rest of apartment himself. Not letting builder to work there, project has to be completed by march2015. But not got possession yet, we and 18 other flat owners have given 80% for tolal amount to builder, now if dispute occurs our money seems to be gone. What we can do? How can we get our money back or, the flat possession,