Crossland instrument console fault

I have a 2022 crossland 1.2 se turbo with an instrument cluster that does not always do the full scale check on turn on.

Sometimes it works properly, other times it goes downward & flickers, other times it flicks up a little, This happens to all 4 needles.

Vauxhall have allegedly tried software & have definitely changed the cluster & it still does it.

Going downward indicates it is getting reverse voltage. 

Any ideas? The main dealer seems not to care how long they keep my car.

If I had taken a courtesy car my wallet would be a lot lighter.