Builder not applying for an o.c

We had bought a flat 2 years back. the bldng was under construction back then n we were promised to get it within 6 months.. However it kept getting delayed.... The project started some 5 -6 .years backk..... ..but noww izz fully ready...the builder is ready to hand over the keys.. But would not apply for an O.C. The BMC water supply wd come only after we get the O.C...which means we wouldn't get the possession completely.... Theres always a new project of the same blder coming up around the same complex....n he keeps delaying our project saying......hel give possession of all the projects togedr.. He started wrk recently on a new project stone throw away from our bldng....When we tried approaching him he said...hel apply for the OC nly after 8 mnths...once that new project has finished...we are staying on rent fr the last 2 years....cant afford more than this noww......plzzz help me....i dont know what to do.....or how to goo about in this matter....the society doesnt exist..soo that we cd collectively complain...it seems most flats were purchased by INVESTORS who dont care about the possession or OC as they wont be living there. I think we are all alone..n trapped.