Deviation in approved plan and construction plan: Builder take example of AKRAMA-SAKRAMA.

Q: i have a question, i came across one builder in outer ring road, he is constructing one building G+4, in fact i have booked the flat with him and then he have shared the site true copy and rest of the documents for verification. the bitter truth i came across is that in the site plan and the working plan have huge difference in the SQFT. the approved plan says that the max sixe of the flat should be 600 SQFT and the builder is construction 950 / 1100 / 1180 / 1360 SQFT of size of flat. when i asked him the details, he told " all the flats in bangalore get constructed this way only, there is a bill AKRAMA-SAKRAMA , if it get passed by the govt. all will become legal. can someone put more light on this kind of deal ?. BTW i have canceled the booking and took my cheque back with no problem from this builder.