rear axle

My goofy ah overtightened the original axle on my Boardman MTR 9.0 2021 medium, decapitated the poor thing... It's marked with: 20e3 qr52m-12-172-p1.5-12, I haven't been able to find a suitable replacement. I measured the axle at 174mm excluding the head, 12mm of threaded length, and a head...

Today I noticed a noise on my Rise H15. I thought the cassette was loose, but it turns out that the threaded boot on the non-drive side of the rear axle has come loose. This holds a washer in place that is now dancing around. I see no way of tightening this. Even with the axle tightened to its...