Hotpoint FF40X wont stay cold?

My fridge freezer has been fixed 5 times in 5 weeks. Just about everything has been replaced. The compressor, circuit board, pipework, defrost heater, the lot. It has also been re-gassed.

However the problem remains. after a few hours the two lights at the top flash orange along with a beeping.
The freezer defrosts and the fridge gets warm.

Hotpoint engineers haven't got a clue. Everytime they plug there laptop in, it "apparently" shows something new at fault.

Losing patience with this. Had no fridge/freezer for six weeks and its getting close to xmas.

Help, before I chuck the thing in the skip!