Builder charging extra for parking

When I purchased my apartment in 2016, my builder said I need to pay for parking allotment. Different values for stilt and open parking. I paid for open parking since I was strapped for funds. He gave me an allotment letter showing the position of the parking as I wanted. Three years went by and the builder converted most of the open parking to closed parking as he needed to build a club house above the parking. Now he is claiming if I need to get the parking ar the spot assigned to me then I need to pay the closed parking charges. If I want open as assigned I need to park at another wing which is very far away from my building. What should I do. Can he do this?