Very strange.

Got a heating controller that, basically, you set separate times from heating and water.

At the moment, heating is off. But we still need hot water.

Trouble is radiators still come on even when its off. (But obviously, boiler is running heating the water).

Any ideas?

Not knowing much about it but I assume that in this case something should be telling the system to fire up, heat the water but not send hot water into the rads?