The key issue here is whether the problem you are experiencing is a fundamental design flaw with the vehicle or one that is unique to you or only some other owners. You may wish to try online forums or Kia owner groups to see if others have experienced the same issue, and it may be worth making a complaint to Hyundai UK. It could be argued that the fault does not stop the vehicle from being driven, but at the same time inoperable safety systems are a significant issue and could raise the issue of liability if the car is not providing the protection it should.