Bptp park 81 faridabad
Cancellation after 80% of payment

I have purchased a floor in Bptp park 81 project faridabad of 275 sq yards

If have already paid 80 % of payment and had not paid last 10% demand now m ready to pay it with intrest but they r not taking the Amt and saying that my allotment is cancelled. How can they cancelled after paying 80 % of payment.

Pls suggest what should I do.