Parking allotment in a redevelopment Appartment

We had given our apartment for redevelopment. During the initial discussion we had requested the developer to split our Flat in 2 No's of 1 BHK instead of the 3 BHK that he was supposed to provide us. Also we requested him to provide us 2 No's of Hydraulic Car Parking in the redeveloped apartment. 1 Car Parking will be free of charge against the surrendered 3 BHK flat and we will purchase the 2nd Car Parking. This was agreed upon. The Car Parking amount was included in the payment schedule and was communicated to us via WhatsApp stating that the Parking amount shall remain payable at the time of final payment & possession of the flat. We paid him as per his defined installments for the increased area as per his requests. Now during the final payment he has removed the parking amount from the payment schedule stating he does not have any parking space left so he cannot provide us any parking space. When we confronted him with the WhatsApp communications, he said these do not hold as a commitment. Also as you haven't paid the amount we are not liable to provide any parking space now. For us this is a breach of trust. What can be done now, when there are no spaces available?