Personally I stick to my guns - fortunately my pieces are re-sellable, so if I do give a refund upon return of an item, there's generally nothing lost on my part but the listing and shipping fee.
As for your work, as it's made to order, the final product may not have been finished, but the bulk of the work had been. You shouldn't have given them a full refund.
But what's done is done, of course, and if you've not received a negative review then that's something. Unfortunately, you have lost your time, and that counts far more...