I finally won... I have achieved 1941 on my car via the garage. I like many people had 1896, crashes started and became more frequent.
I complained to the garage, they reinstalled 1896, it went back, tech support said I needed a new MIB3... once it arrived it was fit... on 1668. Garage swore blind that it was the latest version available for that MIB. I gave them the benefit of the doubt - days later, issues reoccurred and a butt tonne of other little niggles which you could find in forum posts for two years ago.
I took it back yesterday, "fix it - or we're talking returning it the car". It turned out that MIB3 they'd replaced mine was missing a recall fix - so their systems wouldn't let them upgrade it. Once they figured that out with Skoda Tech, applied the recalled fix, it went through 17XX, 18XX to finally 1941.
It now appears to be fixed, everything just works, no crashes. I "caused" a bunch of this hassle by pestering them to fix it, they decided to swap out the MIB3 a week before 1941 was released. I suspect if I'd just waited it'd have been easy to upgrade, either by garage or the 1941 firmware floating around here.
I'm gonna go back to enjoying my car and not feeling slightly angry/annoyed when I see the infotainment. Huge thanks to everyone here.