Substandard parts

Korean spares sell substandard parts. I have a kia sedona v6. When i got it i fitted alfa brake discs it lasted 5 years and 42000km no shudder. I the bought a set of disc from korean spares. At 800 km its started shuddering. Got so bad that it was dangerous to hit the brakes above 100km/ h. When i went back to them to complain i was told its driver error or in their words abusing the brakes by braking to hard ( by the way its my wife's car)I then took them to get skimmed thinking it would fix the issue. It lasted 650km and shuddering again. Reason i bought from Korean is that the discs was R1500 cheaper than the alfa discs. I should have stuck with the alfa discs. Will never buy form them again and will never recommend anyone to buy there.