Super area difference after possession, feeling cheated

Got possession for my Selectra Developers flat in Dadri last month. Yaar, the super area vs carpet area difference is shocking. Brochure mein kuch aur tha, possession pe kuch aur nikla. Matlab, 100 sqft ka farak, itna paisa extra de diya for nothing. Kitna common hai yeh Noida Extension mein? How did others manage this?