Liebherr Premium BGNDes2986 BIOFRESH Freezing

I have a Liebherr Premium BGNDes2986 (9984016-00) side by side fridge and Bioresh/freezer. About a two months ago the bio-fresh suddenly displayed '0' when it usually displays '1'. It then froze everything inside. I defrosted it and it seemed okay until last night. Same thing happened, this morning everything was frozen. I switched off the bio-fresh on the top control panel, but when I got home tonight it was still frozen, -20degC

I'm confused why it seems to still be cooling when switched off, and why it suddenly freezes up or no reason. The door has not been left open, the alarm has never sounded, I haven't done anything unusual.

Does anyone have the pages from the service manual for the Biofresh, including the fact codes?

Any advice?