Glow Worm Ulimtate 50FF Fault?

Our boiler comes on with the timer and goes off with the timer all ok however it does not recognise what temperature we set the thermostat to. It just turns itself on and off as it feels like it... So sometimes it gets so hot we have to manually turn it off or sometimes it pops its own red button.

We have replaced the thermostat and no change and were considering the control panel, however as that brings the heating on at the times we have put in i presume that is not a fault. Someone did suggest it could be a motorised valve is this right?

C Walsh
November 2009