I am not sure which compound you are looking for, but there are a few iron/tin/silver compounds in the available databases, e.g. disilver-iron-tetrathiostannate Ag2Fe(SnS4), silver-iron-tin-sulfide (Ag,Fe)FeSnS4, disilver-octathioferro(II)tristannate Ag2(FeSn3S8), disilver-tin-iron-triphosphate Ag2SnFe(PO4)3, plus a few more. Do you have a complete formula to share?
Most crystal structures are sorted and published into two databases. The Cambridge Structural Database (CSD or CCDC) contains only organic and organometallic crystal structures. The ICSD contains only inorganic crystal structures. Your structure would be deposited in the latter.
ICSD:
http://www2.fiz-karlsruhe.de/icsd_home.html
As mentioned by David, structures from the CSD can be freely requested from:
https://www.ccdc.cam.ac.uk/structures/?
However, your institution may have a site license for the offline CSD software, Conquest, Mercury etc. that are incredibly powerful tools.
Further, if you are a member of the Royal Society of Chemistry (RSC), they provide free access to these databases: