Collaboration agreement

Hello sir, we entered into collaboration agreement with a local builder in our locality in Delhi where the builder will construct stilt parking + four floor and one floor and parking area of his share to be given to him. After we vacate the premises he latterlyforce us to make the basement also in the building citing reason that this is compulsory as our road is commercially notified road. Now he started building the basement but the quality of the foundation is very poor, he hasn't appoint any structural engg for the same nor he has the drawings for the basement.. and we appointment structural engineer and he certified that the foundation of the basement as well as building is tooo weak to withstand load of even 3-4floor We haven't got the agreement registered in Court or the mcd. Now my question are 1. How can we cancel the agreement with him 2. We just need to file the case the in court's of law for cancel the agreement or do we need to get the eviction also from the builder. 3. As father and mother both r bedridden and their last wish is they want to see the newly constructed house, if we go for litigation how long it will take to get the possession back from the builder. Pls reply Thanks Anoop