Alchemist Infra Realty — No money refund

Address: 107mahatma Ghandhi road Kolkata 700007

Dear Sir / Madam,
I am Nadeem mukhtar ansari. I invested 5000 rs. in Alchemist Infra Realty Limited on 18.10.2010
They gave me a certificate of property of 5000 Rs.and promised me to give 50000 rs. after 16 years on 18.10.26 . its has been already matured but till now i did not my money back .
Please help me to back my money .They are not picking up my phone.
details : certificate of property
Allotment No. AIRL/RD00023688