Re: fitting of thermostat beko fridge/freezer
You should be able to work out which is which by tracing the origin of the cables at the compressor terminal block and doing continuity tests on each cable in turn.
Although most of us on this site know the answer, we can’t tell you in case you do it wrong. In law you could hold us responsible, and as you state there are three colours you have already made an error by omitting/dismissing the earth cable, the most important of the 4 wires present.
Kevin