I have a sealed fully pumped system. Boiler is a Worcester Bosch 19/24CBi. Programmer is a Honeywell St699. The installation is about 5 years old. The boiler is now ignoring the programmer and both the water and CH thermostats and therefore runs permanently. It can only be switched off via the main switch. The system has been regularly serviced but I can't get the installer interested in fault-finding ( too time-consuming ? ) All ideas welcome.