"He who marches out of step hears another drum." ~ Ken Kesey
I agree with ericheartsu,Can't sell someone else's product and not expect to pay (them) even if you printed it. You can require to get them back and trash them or use as test prints. at this point, me will want confirmation that they were destroyed or used as test prints. You could cut the print in the center. of all and show him the box.He also can't expect to "keep" the incorrect shirts for free either. Thats stupid.
I did find out from the customer that we had printed 175 shirts and he has sold 100 of them but was unable to sell the other 75. That is where my problem is, I think he sold them while they were hot and now it has died down so he wants me to pay for what he did not sell.