In-case it helps anyone in the future, I by chance found the location of my fridge thermistor on the Beko CXF6114S. Fridge was way too cold, sub-zero on minimum temperature so I replaced with 4394720285 and all working well again.
I cut a 150mm wide by 60mm high hole which started 200mm in from the left side and 200 mm down from the top.