Bbmp sanction plan different from working site plan

Hi, I have booked a 3BHK flat in an under-construction building but came to know that in the sanctioned plan it was a 2BHK flat. The builder has kept the sq. ft. area same but took a balcony inside and made it a third room. And added one extra balcony also. The setback deviation is not there. The building has lots of open space on all 4 sides. My question is: is this a major deviation? Can I get an OC for this?