Zanussi ZX 56/4 SI low fridge & freezer temperature

If anyone could help me i would be extremely grateful. Appliance is only about 2-3 years old.

Basically as it says in the subject title…the temperature of the fridge and freezer seems to be barely above room temperature in the fridge and only just keeping items barely frozen in the freezer.

I have tried turning the temperature setting to max and there seems to be no difference in temperature no matter what setting its on. The black box thing at the back (compressor or whatever it is from reading other postings) is hot and the fridge is making its usual noises.

The strange thing is that about a month ago we reversed the doors around on the fridge freezer and then we have been on holiday for a week and come back the weekend just gone…and this is when we noticed the temperature was lower. Could this be connected in any way? The seal around the fridge and freezer doors seems to be sealed well and no gaps etc

I will try a full defrost at somepoint as this seems to be a common solution to temperature problems but would appreciate any comments or possible solutions to this problem.