Apple REFUSED to Fix our iMac Pro

Apple-certified repair shops are refusing to fix the product. You could go to a third-party repair shop, but they can't fix it because the parts are made and supplied only by Apple who only supplies them to Apple-certified repair shops. Apple-certified repair shops could turn around and resell the parts, but they would quickly get their certification taken away. Legally, they aren't preventing people from repairing their products, but functionally they might as well be.