Not as bad as your's, Bergs, but my daily driver Focus) had been misbehaving for ages - usually the ABS light would come on. Then it'd go off and other odd dashboard things would happen. Then, a few months ago, the dash went crazy - speedo & rev counters dropped to zero and a dozen warning lights came on. Then it'd work again, but not wishing to break down somewhere (the dash and ICU speak to each other) thought I'd better do something.
Searching the web, apparently it's not unusual on Focus's, so sent the dash off to a firm that specialise in fixing them. Not cheap, but then there's a zillion soldered connections on what is basically a large printed circuit board. Everything fine now.
Yours being a Vauxhall reminds me of my previous DD, a Corsa. Had to fit a clutch...... what a caper. Apparently one is supposed to remove the engine, but I opted to drop the box - if only one could. Eventually cut a bit of the 'chassis' away so I could get the box far enough from the flywheel (no way could the box be got out) to fit a new clutch by poking about in the bell-housing. Those cars weren't designed, just bolted together.