TS: are you certain those were dead spots and not floaters in your eyes?
I don't think there is much the distributor can or will do for free with fungus lenses.
The retailer received goods in brand new condition.
With bad storage facility, lenses spoilt. It is fault of retailers for not keeping things well.
Consider it bad luck for this retailer.. Also, such high cost items, they will not let go for cheap unless they have other retailers they do back to back trade.
To be fair, quite a number of reputable shops had defect brand new lens in their inventory. But the more reputable ones may have their ways to remove them from inventory.
Ethics is an expensive cost to the company.