If we rule out the problem being frost stopping the coolant leaving the elements and circulating around the appliance, and note that both fridge and freezer are running warm, I would tend to think its may be the termostat, control board or compressor.
Thermostat fault - there are two one in the fridge and one in the freezer, but as fridge gets its coolant from the freezer, if the freezer is running warm it restricts how cold the fridge can get. So I would check the resistance on the thermostat for the freezer, best accessed b removing the control panel.
Compressor fault - Check if the compressor is warm \ hot to touch, if it is it suggests it is working, if this failed it would be uneconomical to repair, its unlikey the fridge has lost its coolant gas, but again if it has, I would suggest it uneconomical to repair.
Control board - if the thermostat resistance changes as you apply ice or warm water to it, but the fridge isnt calling for coolant then the fault is most likely due to the control board. Control boards cost around £100, make sure you buy a pre-programmed one.
Appreciate if you can rate the service received, if after this evening you cant find the fault, send me your postcode and I will happily recommend someone to come out.