The cord on my Velux blackout blind wore through plastic runners of the blinds. The problem only became apparent after 4-5 years when the cord frayed on the sharp edges and jammed the blind.   Velux are saying I'm out of the 3-year warranty (the blind is about 5 years old). I'm saying that the blind was never fit for purpose as the plastic has clearly worn gradually from the time the blind was installed.   As well as opinions on whether I have a case, I'd be interested if people could chec