A few years ago, i needed to replace a headlamp bulb on a Vauxhall Zafira.
I happened to pass a Vauxhall dealer, so got the bulb there.
In the owner's handbook, there is even a diagram accompanying the simple instruction " turn the bulb holder anticlockwise and remove". This diagram bore little or no relation to what was actually there.
In short, it took a Vauxhall mechanic, with my help, about 3/4 of an hour to replace it.
To even get access to the rear of the bulb holder meant removing the entire indicator/side light module, plus several parts of the air intake system, inter alia.