Hi, I think you have to fight in this matter. I would like to say that you can check the approved plan and talk to the builder regarding these diversions in approved plan.The car park is one of the important amenities. Should you pay for car parking? If you have a valid document process for legal steps... gather all apartment owners and talk to the builder.
I can understand your concern. I would like to suggest you to have a thorough discussion with your builder and ask for the forward plan. Also, you can consult a reputed lawyer to know about the legal aspects of the order and what is mentioned in your property agreement.
Thanks.