CAn you advise which lights are flashing, and if you hear the motor start when you enable the super frost\freeze function?
This sounds like a control board failure, resulting in the fridge not calling for coolant.
The alarm light will illuminate if the freezer is at a extreme temperature (eg above -10), super freeze flashes when its enabled but not reached an adequate temp.
If both fridge and freezer are not at the correct temp, its likely to be the control board which is best part of £100 from here, if it just the freezer compartment it could be the thermostat which is only £30 from here.
If its only one compartment which isnt cooling I would suggest its worth getting an engineer out, otherwise I would think this would be uneconomical to repair. Please provide your postcode if you would like me to recommend a engineer in your area.
No problem, appreciate if you can rate the service received.