Artha Property — artha sharanam project - waiting for plot registration / refund of money from last 6 years

Booked two plots (19 and 20) in artha sharanam project in 2013. We also paid 80% of the total plot cost.
From last 6 years we are just waiting for the plots to get registered.
Finally 1 year back we were asked by artha to cancel the plots and get the refund with 10% interest. We agreed and submitted all the required documents.

It has been a year now but we haven't got a single penny back from artha.

We are not getting any response also from them.