Consumer Redressal

i have booked a flat on allotment letter in fountain square project oshiwara by sonata realty (Azam Khan) and shubh builder (Govindbhai & Arpit Samani) mumbai in 2009 with completed promised in 2012. The construction did started but then it was on hold due to many statutory issues and also caught up with environment issues.before one year environment clearance received but only for 23 floors while the builder has booked till 39 floors. inspite of this clearance til date they have not received plinth cc. also it seems they have already booked around 27 floors @ 40% payment & 4500 psf rate in 2009. Rates in the vicinity are very high like 15000 psf. We have formed a group of many victims. how we should pursue this case. our aim is to push builder legally to complete project in specified time. Getting interest or compensation seems very less. Builders are well known to be fraudulents and their other projects also have some issues. also they are not giving any details/proofs of what they are doing to solve the issue