I got them through who I would say is thought to a reputable seller on this forum.
Do you mean this was effectively a private sale then? If so, "buyer beware" is the phrase used or did yo mean " folk on this forum consider them to be a reputable seller" ?
It seems fairly simple to me though, if the seller lost some bits in his keeping that belonged to you, then he has an obligation to replace them or compensate you for their loss.
If they won't play ball, small claims court or Judge Judy, depending where you live.
Edit, if folk here consider them to be a reputable seller, then it's not "him" is it?