Sold as seen shouldn't come into it. If they were actually sold as R32 calipers, the onus is on the seller to make sure they are rather than the buyer to spot the difference. If this was on ebay, you'd probably win a dispute case hands down and have your money back quick.
If there were advertised as vw/audi calipers only, then you've not got much of a case. Hope you get it resolved either way ;0