This is a bit strange in as SEAT seems to suffer from plastic light clusters failing more than any other VW Group marque - or an awareness of it gets more public exposure. Is this due to the SEAT styling being more "exotic" than the other VW Group marques, so more risks are being taking over design and so plastics fail.
My daughter's late 2009
Ibiza SC had water ingress issues with both the rear light clusters which I sorted out by applying sealant into the joining areas of the plastic parts. A friend of my wife, who thinks they have a very good relationship with their local SEAT dealership, has had over the past 2 Leons, within warranty, had to pay for getting rear cluster replaced, one twice - but I'd doubt if they would have contested these issues. I've not seen them face to face for a couple of years, so I can't say if they have also had this high level brake light issue.
Okay, my mate's son had to replace a rear light cluster on his 2006 Polo recently, but at that age, not so much as an annoying issue as plenty good quality rear light clusters are now available via scrappy's.