Can A Housing Society Cancel The Site Allotment For Not Building A House

I have been allotted a site in Bengaluru from a housing society in 1989-90. It was a lease cum sale deed which would be for 10 years. As my mother did not know about this absolute sale deed she has not entered into absolute deed. Now the society has written a letter stating my site allotment has been cancelled as one clause has been violated. the clause is that one has to build a house within 2 years of allotment. Now the absolute sale deed is not done and only lease cum sale deed is registered, and we have done the khathe and have been paid tax regularly, what is the consequences of it. We had not received any letters, as we had changed the address. They called us on phone and have taken the address and have sent the letter informing us that they have cancelled the allottment. Kindly advice.