Delhi Development Authority (DDA) — surrender flat but not get the refund

Address: New Delhi, Delhi

I have submit all the docs to dda for surrender of my flat against application no.0931759 in feb2015. But till now i have not received till now. And dda employees do not pick up the phone.if wrongly they picked up the call then they said its wrong no. And even in dda office they were not told us the refund status. They always said submit the docs again. I have already submit the docs two times.i am also working person. How can i go daily to dda office for getting the refund status. Services of dda & their employees were very disappointing to customers.