1000 miles in 6 months is not insignificant use – and as has been said, if anything, it’s just a warranty claim on bearings, nothing to do with “not fit for purpose”. In an old job, I actually went on some extensive training with Trading Standards, and they told us about the sad fact that every man and his dog now tries to use that to force a retailer’s hand. All a retailer/brand has to do is demonstrate ratio of units sold to failure/return is decent and it would be laughed out the door. DT have sold hundreds of thousands of these units. If they were unfit for purpose, the internet would be awash with rumours/horror stories/”don’t buy DT” posts.
Given you also mention that it was fine when you checked it 2 months ago, any “not fit for purpose” claim would be shot down in seconds as insufficient regular checks (suggest at least bi-weekly given mileage stated) haven’t been carried out by the owner. To frame this, I do lots less mileage than you, but check all bolts front to back on the bike every single week.
I’d suggest the approach to take is a friendly call to CRC, be nice, be matey, explain to them the bearing has collapsed after only 6 months and can they help you out if you email them some pictures. Get all shouty/demanding, you’ll likely get your absolute minimum you are entitled to, which given lack of regular checks will likely be sweet FA.