Poor service and quality

I purchased two pairs of falke socks from superbalist. When I received them, I was appalled at the poor quality and immediately requested a refund. They collected the socks but only refunded me one pair and said that the other pair isn't refundable. Please note that the only difference is that the one pair is white and other pair is black. I've contacted them and all they could say was that it was labeled incorrectly on their system and won't refund the other pair. They didn't even put the money back on my credit card for the one pair and put it in a wallet for me to make more purchases which I will never do again with that online store.