takealot.com defective item that could not be exchanged nor refunded

I ordered printer cartridges from takealot.com and all the colour cartridges worked except the black cartridge. When I tried to ask for an exchange not even a refund, I was informed that this item is non-refundable and cannot be exchanged either, especially after it had been opened. So takealot.com how would I know that the cartridge is a defect if I don't try to use it in my printer? I see that in the reviews many people have complained about the same and have received defects. I would expect that a brand such as takealot.com should consider who they are associating themselves with and not sell defective, poor quality products which are non refundable and cannot be exchanged for actual working products.