electrolux fridge/Freezer ER3396B fridge temperature fluctuation?

Recently the temperature in the fridge compartment has fallen below freezing - how far below I don't know but enough to completely freeze a glass bottle filled with water. I have put a thermometer in the fridge to try and see what is going on and most of the time this shows 9 degrees c. This has happened 4 times since April of this year and each time the fridge has regained its normal level on its own. The temperature dial has not been moved.

The freezer is working although the alarm light is flashing and has been for years. The freezer lights for -18 and -21 are lit up.

Any advice appreciated.