Terrible customer experience

Hi. My boyfriend purchased a set of pajmas which are too big. In March 2017. We went to return it today with the receipt. I had been away and only managed to try them on recently. We were however told that it was not possible to exchange the item for one that was exactly the same price, as the item went on sale and that the refund period had lapsed. I understand that A refund was not possible however surely an exchange could have been accommodated? Isn't that in line with the Woolworths customer experience? im really not satisfied with the experience. This happened at the Woolworths in rivonia village shopping centre Johannesburg