Delay of Apartment flat possession for more than a year

Dear All, I bought a property in Bangalore East in 2013 Mar and the apartment is supposed to be completed and handed over for possession in May 2014 but actually it wasn't. I have paid almost 90% of the payment as agreed with the Builder. The Builder is a partnership firm that is run by 3 partners. The problem all started as 3 partners has some conflict issues internally and now one of the partners has quit the project (albeit not officially) and wants his capital investment money back. The other 2 partners are not ready to return his investment and as a result of which all the funds the buyers paid is sitting in the trust bank account and it is directly leading to the delay of the project. inspite of this after we forced the builders to write a compensation in delay of possession of the apartment flat. They wrote and signed it in the Builder company letter pad. Finally, as per the last communication with the builder, they say May 15, 2015 they will give possession with all basic amenities. However looking at the progress, they will not be able to complete the project given their internal conflicts/problems which must be sorted out first. Could you pls advise if we take legal approach, how sooner or later we will get a verdict on favor of the buyers. Also will it lead to further delay of the project if the Builder seeks a hold on the plea? thanks, Buyer.