Parking allotment.

Dear sir,i am in ratnagiri district maharashtra.in our socaity 3 buidings A,B,C are there with 30 flats.builder not constructed B and C building with parking space he says all 3 buidings will park vehicle in A buiding while there is only space of 6 to 7cars adjusted.B and C buiding flat owners park there vehicle in our A building.is it right they can park there vehicles in our A building parking? I purchase a parking with flat.in my sell agreement also mentioned 100 square feet area of parking in index two. in agreement there is not located the area and not attached ground floor plan.buider said not need of that because you are only one member purchase the car parking and he did not give me allotment letter.when i choose flat he locate the parking and i park my vehicle on that place till today.after 5 years created some drainage problems i involve in that so builder get angry and defuse to solve problem and then he give allotment letter of my parking to one his close member living in C building.now the flat owner shows allotment letter in socaity and telling body members that this parking is mine he have no any agreement mentioned regarding parking in sell dead or in agreement for sale.builder and he give me mentally disturbing,what i will do in this case?