We want to cancel agreement of buying. Agreemnet says will foefeit complete amount.

We agreed to buy an unauthorised flat in Puttaparthy because basically none of the apartments here are authorised since the authprisation is only ground plus two. The bulider gave sweet words verbally and said beforemaking the agreement that the flat measures 950 carpetarea to my mother. We saw their plan on their brochures and it said 950 sq ft including common area. She registred the agreement it for 4 lakhs. Now the actual truth comes that 950 is not even built up and not even super built up. My mother sees that they have openly cheated us by putting a small terms and condition on the brochure saying that plansand specification can change. We want to cancel this purchase, but the agreement says yu may forgfeit the complete four lakhs. MY question is/ Can these builders in this place hamlet called puttaparthjy grab the whole agreement amount hwne they are openly changing specifications and lootinf customers by simply taking advantage of their terms where it mention sthat they can change ther specifications. The other question is that They are chartging us per sq ft for the superbuilt up too. There is no percentage bifurcation.s We are paying the same rate for the whole area when in actuality we are only getiing say carpet of 650 sq ft. We are paying for something which does not exist. This is case of Legalised cheating only because the small disclaimer. Help.