Global Enterprises — service person stole screwdriver

Address:

Bangalore, Karnataka, 560043

I called aquaguard customer care bangalore for a service request.
On 8th july, 2018 two people came from "global enterprises".
They did whatever was required to service the water filter.
While leaving they took my screwdriver without my consent.
I called them several times to get it back but no response.
Its not a matter of just a screwdriver, what if they had taken some costlier item?
If it was by mistake then they should have returned it by themselves.