Turn boiler down or room stat?

[flameport]

The room stat is in the hall and we usually use this to regulate the temperature

That is the correct method, however you should just be setting the thermostat to the desired room temperature and leave it there.

Don't fall into the trap a lot of people do which is altering it all the time.
Things such as 'it's cold outside so lets crank the thermostat up' are the quickest way to waste fuel and money.