Payjust now refused to pay me back 300 delivery fee for an order that was sent to me damaged and I returned back to them

My name is Brighten I've ordered 4 gomez drawer on superbalist and paid using payjust now, the order was poor quality and worse part had cracks on it so I had to return it back to them. They charged me R300 delivery fee and now they refusing to refund me that money. How can I pay R300 for something that was returned to them because of thier negligence, weak material or quality and cracked item. I want my money back