AEG Fridge freezer – Freezer temp not remaining cold. Model SANTO C7 18 41-4 i.

Hi all
Took the opportunity to defrost the freezer compartment yesterday and now the issue has started. I use remote temp sensors in the fridge and freezer to make sure all is at the correct temp. I haven’t seen any temp issue until yesterday. Defrosted as normal, all good and watched the temp fall back down to -19C. My joy didn’t last long as the temp then rose back up. I had set the fridge thermostat to 6 initially to pull the fridge back down and then when it hit correct temp reverted back to 4 where it normally sits. I left it overnight and came down to -8c this morning. The fridge holds temp OK. I turned the stat up to trigger the comp to run which it did, down went the freezer temp. The issue comes when the fridge hits temp even if the freezer is at -19c at that point the freezer then starts to warm back up, as it is now:( Am i missing something or is it just one of those things that is a coincidence? I appreciate the model is old now but had hoped it would wait for the new kitchen to arrive before disposing of it:) All help gratefully received[IMG2=JSON]{“data-align”:”none”,”data-size”:”full”,”src”:”https://www.ukwhitegoods.co.uk/forums/core/core/images/smilies/thumbsup.gif”}[/IMG2]

Model SANTO C7 18 41-4 i. Type B256946. Prod 925 694 677

Update: This morning 07.30, freezer at -18, fridge +3.7. home tonight 18.15, freezer at -17, fridge at +4.9. Have monitored from there and fridge temp has ranged from +4.0 to + 5.4 and now +4.5 at 21.30. Freezer which has not been opened has ranged from -17 to -11.2 and then back to -16.3 at 21.30. Is this normal cycle?