Hi, this is most likly to be the termistor (temperature sensor) at fault.
This sends a message to a actuator which controls the amount of coolant which travels to the fridge part.The good news is this isnt a pump of right off.
When you turn the temperature dial in the fridge can you hear the pump start or click noise, another test is to turn on the super frost setting to see if the fridge starts to get cold.However its going to end up as an engineer call out, though I would expect the part to be around £10 and the engineer to be on site for around 45 minutes.
When you open the fridge door either on the bottom left or bottom right should be a stick\plate with the model number can you advise what that is.If I can find the right model I might be able to see if there is anything unique about your model which could fix it for you.
Ok on the control panel where the far left button 'Fuzzy mode' press this so its switched off
Ok turn off the fridge by holding down the temp button, wait 30 seconds and hold the temp button agian to turn it on
keep the door closed, and check the door seal. After an hour and and touch the back of the fridge to see if its cold to touch.
Glad this worked, can you please rate my service today so I can close this case.James