Anyone had a problem with parts of the heated rear screen not clearing, due to it not heating up. Noticed that on the middle sectoion of the top few wires they don't clear on our Fabia, rest of the rear screen clears fine. As the vehicle is only 14 months old I'm wondering if this is covered by the warranty - I've never  had a fault on a heated rear screen beffore.   Or is there some feature that I'm not aware off.