The message
from John contains these words:

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.

Nor should it. The device is trying to shove heat out the back - the
cooler the surroundings the easier this is. The warmer the surroundings
the harder it has to try - and use more power in the process.

The only gotcha is that some fridge-freezers only have one thermostat
and that's in the fridge bit. If the ambient is below the set-point for
the thermostat in the fridge it'll never switch on so the freezer bit
will never get cooled as it operates as a side-show to the fridge. But
that doesn't appear to be the case in your situation.

Whichever course you take, ensure there's good airflow over the back of
the unit - don't pile the top up with stuff that goes back to the wall,
and don't block round the sides/bottom.

--
Skipweasel
Pay no attention to that man behind the curtain.