I have a theory regarding motor manufacturers' quality control:
Every component part of a car is rigorously tested, and any that appear faulty or substandard are weeded out. But instead of going to landfill, they go into making vans. Nothing is wasted. And silly sods like me pay over the odds for these vans because post-Covid alternatives to foreign holidays (ie campervans) has pushed prices up.
I could have bought a similar-age E-class for what my van cost, and here I am, paying through the nose for parts which really should last longer than 5 years. Just shelled out today £430 for a 'knock sensor', and another 140 quid for it to be "coded in" online, whatever that means 
And it's not just Mercedes, it seems no manufacturer is capable of or willing to make vans which are as reliable as their cars. How hard can it be?
I just dropped in, to see what condition my condition was in
T/T: Inspire Monarch, X200 tonearm, Ortofon Quintet Blue. Phono: Project Tube Box CD: Marantz CD6006 (UK Edition); Amp: Musical Fidelity A5 Integrated.
Speakers: KEF Reference 3, REL T9i subwoofer. Cables: Atlas Equator interconnects, Atlas Hyper 3.0 speaker cables
T'other system:
Echo Dot, Arcam A75 integrated, Monitor Audio R852 MD speakers
A/V:
LG OLED65 G56LS, Panasonic Blu Ray, Sony a/v amp, MA Radius speakers, REL T9i sub.
KICKSTARTER: ENABLING SCAMMERS SINCE 2009