Liebherr CUN3033 Alarm and not getting cold enough

Hi, I have a Liebherr CUN3033 Fridge Freezer and the temperature alarm has been tripping even if the doors have been closed for hours.

I spoke to Liebherr who said to reset it by turning the temperature dial to 0, switch the power to the fridge off for 45mins, power it back on, set the dial to 3 (I set it to 3.5) and leave it for 4 hours (I left it overnight).

It’s too early to say if its fixed the alarm issue, but this morning, things in the fridge and freezer don’t seem as cold as they were despite the temperature lights showing normal (fridge is on the 3c light). The compressor has been kicking in and out as normal so the fridge is maintaining what it thinks is the correct temperature.

I removed the panel at the back of the freezer before the reset and there was no ice build up on the evaporator. There are some ice droplets on the back of the fridge wall which I believe is normal.

I had the alarm issue last year and it went away after I switched off the unit to clean it. Seems a bit odd to have to reset the appliance when it’s something that should be left on.

Service Number: 0906956-00

Any ideas what this could be?