Dear Colleague,
In such situation, kindly send one or two reminders to the left employee. If still not responding send legal notice through Advocate from your Organization if the receivable is substantial.
Other option is hold experience certificate and in reliving order mention that he has outstanding payable to the extent of Rs.............clearly.
When BVG information is sort by any agency you may mention this too.
If still not responding, then case can be filed for recovery which normally the advocates will guide further. You may file 2 suits one for breach of contract of appointment terms agreed and the other for recovery. This is a long process but organization has to review the financial outstanding Vs the cost of litigation.
These are some possible steps.