HOW CAN I FIX MYCOMPACT 80E?

BOILER WILL NOT IGNITE WHEN HEATING IS SWITCHED ON BUT IT WILL IGNITE FOR HOT WATER SUPPLY AND RUN THE HOT WATER THROUGH TAPS AS NORMAL,WHEN HOT WATER TAP IS SWITCHED OFF BOILER WILL THEN SHUT OFF ALTHOUGH HEATING IS STILL SWITCHED ON.THEIR IS ALSO A NOISE LIKE A SMALL FAN OR IMPELLER CLATTERING AS THE BOILER SHUTS DOWN. IGNITER BUTTON WILL NOT WORK MANUALLY, AND RED LIGHT ON IGNITER BUTTON IS NOT LIGHTING UP