Hi can some one help please, i have a worcester 9.24 electronic rsf boiler but its playing up, i push the switch to turn the heating on and the boiler fires up and the heating turns on but when it reaches the temperature it turns off and wont come back on the only way i can get it to turn on again is by going over to the boiler and pushing the switch to hot water and then back again to heating and the boiler starts again i have to keep repeating this all the time. can some one tell me whats wrong PLEASE. Thanks in advance...