Expat Properties — I paid 4.55L for 0.5Acre property named Mangalam. So far no registration done nor refunded the money

Address:

B403, Casa Grand vivant, 3rd main ramamoorthy avenue, Kolapakkam, Chennai 600122

I booked 0.5Acre property named Mangalam near Pondicherry in the year 2011. Expat collected full money of 4.55L by 2012. Subsequent to that they have not competed the registration properties. Many of my emails, phone calls were not responded.
Request to refund the money with basic interest rate atleast for past 11 years. It is a hard-earned money and expat cannot take ride on me like this.