Make a report with the better business bureau is you picked it up at his shop. That is false advertising and if you guys had any sort of agreement, it could be considered a breach in contract. You paid for a product, discovered it was the wrong product, and wanted a refund based on the original agreement, but he refuses to honor said agreement. Also, how long ago was this? You have 3 business days to retract from any transaction and get a full refund via NYS business law if the murchandise is in the same shape as when purchased.