Hi my name is ***** ***** I am here to assist with your query.
It sounds like the temperature which is flashing is showing the current temperature, or is being over-ridden by an eco mode or similar feature.
To better assist you, could you please tell me the model and serial number of the fridge so I can investigate further for you?
Many thanks for getting back to me, you can find the manual for your Fridge \ freezer here.
Give me a while to look up the likely causes and I will come back with a suggestion as to how we can address the issue with the temperature control.
The operational temp for the fridge is between 7 and 1 degrees, so it should accept you changing it to 3 degress.
At what point is the value changing back to 5, is it after 5 seconds?
I ask since the manual states on page 8 "After five seconds, the display reverts to the actual temperature. The unit will then work to adjust to the new desired temperature".
The reason for the display blinking is because the fridge has suddenly risen in temperature, which may have been caused by frequent openings, cleaning or from warm food placed inside. The digital display will stop blinking when the refrigerator returns to the normal temperature, I suggest you give it a few hours without touching the temp setting or opening the door, and see if it stops blinking and the temperature settles.
If the temperature continue to increase, it may be worth checking the back isnt blocked up (air need to circulate behind it), if no signs of anything blocking air flow manually defrosting the fridge and freezer, leaving it switched off and ensuring the back radiator cools down. I know it should self defrost but this is the last resort before calling out a engineer to investigate further, as it could be there is a control board fault or the coolant gas needs to be re-energised.