I'm in switzerland and the price of second hand bikes still sucks bad tbh..
Most people ask way too much and people are ready to pay too much.
The winspace isnt such a bad value tbh yeah the frame is expensive but it seems to be top notch quality

i have a friend in paris trying to buy a really nice BMC for 1.1k right now. ad posted 0 day.
it seems that the good deals are gone very very fast. then you're left with a bunch of overpriced bikes that people dont really want to sell. a friend in germany is looking to buy a small bike, the stuff she's showing me is pretty atrocious.

at the back of the cassette, there are 3 small screws (i have the half alu, half steel ones). i had one instance where one screw was getting loose. i loctite-d everything and it's been fine since.
i hope you're not asking a refund because a screw you can tighten & lock is getting loose?

by way of update, the 3rd derailleur (er9) that died on May 18th, I'm yet to get ltwoo to provide a warranty replacement. it died like the others, for no reason.
someone suggested that - somewhat magically - resetting the whole thing with new batteries could fix the issue, it didn't on mine. I capacity tested all the lithium batteries i put in these groups, i'm pretty familiar with lithium things so i doubt there's something obvious that i missed in the battery department.
So it's now Jun 21st and my reseller is saying that ltwoo support is now full on ghosting him. He's now trying to speak with the sales rep. He says he's pissed off himself that the company is behaving like that. Now my reseller isn't reactive at all, i have to chase him 5x before he replies, but i do believe him when he's saying that he's being ghosted.
i've now put over 5000 km on mine, and other than charging problems, it's been flawless. my friend who broke his wheel weeks ago is now back on the bike, so he's ticking miles on the 5th RD, so far with no problem other than calibration to avoid chain drops.
I've installed 2 replacements and these have been working fine, but that's on under 500km together.
the worst thing in all this is the behaviour of ltwoo. a beta product with a ghosting manufacturer is just bad news.

Are you a factory or a reseller?

I know and this is clearly marked on the bottom bracket I got. It doesn’t even go in a bit it doesn’t grip the thread it’s as if it’s the wrong size. The non drive side goes in smoothly btw. Haven’t heard back from Wendy (about this and some paint issues I discovered while working with the bike) normally she was very quick with her response let’s hope that’s not a bad omen.

Please post pictures. i want to believe it's user error, because otherwise it's the worst QC control in recent history, and Lightcarbon is very well regarded. And they know we discuss their stuff on here.
you may want to message madpec on YT, as he's a bit of a guru at facing & machining bottom brackets, especially T47 now that he has the (insanely expensive) tool.

coat hanger, spoke? hydraulic hose maybe?
you can buy an endoscopic camera for very cheap from Ali / amazon, in case you want to actually see your problem.

Value for Money: The bike offers incredible value for money. With the seatpost, bars, frame, and accessories all for around £550 delivered, it's hard to fault.
The total cost for the build was around £1250.
The Elite wheels took 65 days to arrive, but I took advantage of Choice Day and got them for £365 delivered.
The R9 shifters, which were £35, work well with Ultegra 8100. The only downside is the thumb shifters, which make it impossible to shift on the drops.

Impressive, it's a lot of bike for that money. Well done.