Car parking lot not mentioned in sale deed

Dear Sir, I am in Chennai. I bought a flat of 955 sq.ft. which is a 2 BHK one in the 2nd floor. There are 7 flats in my apartment. In GF 1 (2BHK flat), in 1st Floor 3 (2 2BHK flats and in 1 1BHK flat) and in 2nd Floor (2 2BHK flats and 1 1BHK flat). When I purchased my flat, the builder said all 2 BHK flats have car parking (i.e. 5 flats together and all of them are pretty much same size) and while I purchased my flat, the builder did not charge anything extra for car parking (he said he was giving it free since he could reduce sq.ft price that he offered). However he did not mention anything in sale deed or issued any letter that tells that I have a car parking allotted. After 2 years now, he says he is reducing the car parking lots and he is going to make only 3. He says he cannot give me a flat since nothing is mentioned in my documents, In my flat, excluding mine 2 2BHK apartments have been sold and of which for only one flat he has mentioned of alloting car parking in the sale deed. The other 2 flats which are recently sold and yet to be registered and he is going to include car parking in the sale deed (that's why he said he is converting 5 into 3 now). This is all because the one 2BHK flat in the ground floor is constructed without approval and it is making car parking difficult for 5 flat owners. Now I - who went by the word of trust - is cheated. I would like to know is there anyway I can claim my car parking based on my UDS or through any other means by going legal? Now I have a car and it is pretty urgent I need to take some action.