silly question have you changed anything else in your kitchen e.g put the microwave on top or next to it? the difference in temperature can have a big impact on a fridge tats getting on a bit... one other old trick switch it off empty it tip it upside down put it upright again and switch it back on again....
Is the compressor running continuously? If so, it is likely that the refrigerant gas has escaped – and the unit needs re-gassing. Otherwise a common fault on many a fridge is the thermostat giving a false reading.
Personally I would expect a fridge to last considerably longer than 7 years – after all, it only has one moving part.