Sabre HE Combi boiler fault?

Hi, I've got a two year old Sabre HE combi-boiler. The heating and hot water is now not working. The green light is still on (no red) and the boiler is firing up when trying to use hot water or heating. It seems to be staying on and not shutting down, which I thought it would do if it was a faulty pump. I've tried resetting but it's made no difference. Any help would be appreciated, thanks