Dear Sir,
would you please correct your untrue statement at youtube that these parts are from me?
True is that you (respectively your dealer) received detailed information about my “crackling noise repair kit”- but neither you nor your dealer got my original parts!
Fact is furthermore that the parts used by your dealer are not identical to that of my kit.
(That’s very easy to verify optically - just look at the pics.)
Your dealer was obviously not able to understand the intention of the kit, moreover that also not able to recreate it properly.
That’s of course leading to the suspect that the dealer also did not use the correct lubrication component, which is very important.
My kit was composed of very special parts and their interaction, on top of that manual fine tuning - shown parts are standard, I bet.
For a detailed parts specification please refer also to below mentioned thread.
And most of all - the kit is named “crackling noise repair kit” - and definitely not “worn out bottom tube repair kit”.
The purpose of the kit is not to “increase the surface area” - it is a proposal to eliminate seizing (or galling) between the frame, the cup spring 363 (367, 367-3) and the washer 364 above, and again; the crucial part of the kit is the anti-seizing compound Never-Seez Nickel special.
http://www.neverseezproducts.com/purenickel.htm
Using this kit for a wobbly wheel doesn’t make any sense - it was developed only to repair the creaking/crackling noise issue!
Well, perhaps my information was incomplete or faulty, please judge yourself.
I’ve removed the password from the regarding images album and opened a new thread with the complete information; also supplied the untouched, old document version and resized pics to fit the forum: crackling noise repair kit instructions
Coming back to your personal issue I’d like to mention first that - considering above - I can’t take the statements of your dealer seriously; all these things regarding missing or substituted parts, the use or not-use of Loctite and the ongoing belt issue doesn’t speak for reliability, sorry for that.
But let me try to explain what is wrong with your bike,
I’m indeed sorry that I have no idea why (exactly your bike is showing that much wear in a short time). 
At your video “A bit more bad luck”, when you’re showing the wobbly rear wheel, it’s very easy to notice that even the belt tension varies dramatically by moving the wheel. This belt behaviour is telling us without any doubt that the distance between the rear axle and the bottom bracket axle is floating - and the only plausible reason for that again is a (dramatically) worn out hole of the bottom tube!
Tube and insert 100-07 had to be replaced…
In fact, due to the using of some thicker washers, your dealer just squeezed the bottom and the seat tube together - the joint is now stiff (it seems) but under higher load (=while riding) it is still moveable (and still leads to belt twisting).
I think it’s easy to explain the malfunction of part 338 under above mentioned angle of sight:
You will surely agree that a force which can cause a warped disc must have been high.
The force’s direction was more or less parallel to the rear axle.
One could say also that the belt moved the whole wheel to the left side (or say it tried to push the wheel off the axle).
If you imagine part 338 now as a tube (fixed by the wheel bolt) with a washer attached in the middle (the cut-off flange), I don’t wonder that the flange was simply punched outside - next to it (seen from inside) is the much harder inner bearing ring!
