Bosch KGU3201GB/01 FD 7511 – Not staying cold

Fridge freezer started playing up when daughter was house sitting.

It is not displaying any error codes, its just that it is taking an age to get down to the correct temperatures (4 and -18). I took around 20 hours for the freezer to reach -18, its empty and no one was opening the doors or anything like that. Once the desired temps are reached it stays like that for a few hours, long enough for us to start thinking that it’s going to be OK. But, then we hear the alarm beeping and can see that the displayed temperature is much higher again.

In the past the FF has had circuit boards replaced (twice I believe) but has been OK for quite a few years now.

The only other thing of note is that the compressor has started making quite a noise as it stops running, a clonk and a shudder followed by silence. No appreciable noise when the compressor starts up though.

Any ideas or suggestions much appreciated.