Issue with wiser not reaching set point.

[Lobman]

We have a particular room in our house where the wiser hub doesn't ever seem to manage to get the room to it's set point. It's the coldest room in the house.

We tend to set the temperature to 18.5C. however the wiser only ever gets the room up to about 18C when looking at the data it tends to keep the flow temp low at around 50C in an attempt to gradually heat the room but never gets there. 

The only way to force the room temperature higher is to set the room temperature to 30C which then fires the boiler to full temperature and heats the rad up.

Is there a way to fix this? We don't seem to ever be able to get the room up to temperature without manual intervention?