VGN Jewellers — Refund of investment in gold scheme

I deposited money in the lump some gold investment plan with the VGN Jewellers, Mulund, on 19.08.2016 and it matured on 19.02.2021.
On approaching them it was told that the maturity amount will be refunded soon.
Yet there is no response from them.
A legal notice was sent, which was not received by them.
Please help.