Without the information requested in my previous response, I can only give you a general answer, but I hope this helps.
This indicates temperature issue and/or an air flow problem due to heavy ice build-up inside the rear wall of the appliance.
Please try this to solve the issue:
Leave it unplugged and empty with door open for around 12-24 hours.
Then plug it back (expect some water on the floor) and wait for another 4-8 hours so it gets back to optimum temperature.
The problem should be resolved.
However, if the issue appears again then the problem is with defrost operation.
You will have to test/replace the temperature sensor and/or defrost heater element to resolve the issue.
Please let me know if you need me to clarify anything or if you have any additional questions-I am happy to help!
I hope you enjoyed your experience with Justanswer UK today.
Have a wonderful day.