Car parking issues

My apartment builder has taken 1.5 lacs for covered car parking and has give 8X13 feet car parking. The car parking has extended into common area where there is vehicle movement . 3 feet length of parking is exposed to sunlight and rains(in case). I tried to convince the builder he is not agreeing and said he cannot allot a new parking. Builder has cleverly exclude the amount of 1.5 lacs from agreement, but i have a calculation sheet which i received from his official email id ,which mentions t