Whirlpool FRSS36AF20/2A+ Fridge Not Working/Freezer Fine

Hi,

We’ve had two different engineers come round to look at the fridge. There was an ice build-up between the fridge and freezer which they got rid of but otherwise, they weren’t able to diagnose the exact problem. They have suggested replacing several parts including the baffold, heater and I think thermostat?

After the 2nd engineer came round, we left on holiday and came back to a fridge that was once again at 4 degrees but after a day or two of use, it has returned to a balmy 12 degrees or so.

So given that the fridge seemed to return to a normal temperature when the door wasn’t being opened, does that give any clues as to what, if any, parts we should replace?

Any advice greatly appreciated!