Legally, they are liable for more than 90 days, just because it's b-grade doesn't mean that they can get away with not offering what they're legally required to. This has been pointed out to them loads of times, that they should change what it says on the b-grade item pages, but they've yet to do so.
But yeah, even b-grade items are covered by the sales of goods act, and the only things the sales of goods act won't cover, is issues that they make you aware of prior to you purchasing.
But yeah, even b-grade items are covered by the sales of goods act, and the only things the sales of goods act won't cover, is issues that they make you aware of prior to you purchasing.