Refund from Adidas

My son bought sneakers from this website and what a disaster. They took the money and apparently they attempted to deliver according to the courier their 3 attempts failed but my son only has a record of one attempt when he was not home and asked them to deliver the next day which they never did. The courier then said the item was sent back to adidas warehouse and signed for by Cindy on the 26th November. I attempted to call adidas to follow up on the refund but you hold on forever on the call. I then sent a email 4th Dec still no response. I need the money refunded please.