Just had the same problem with same boiler. The solution with mine was that the divertor motor (three way valve) had failed.
If you drop down the front of your boiler by loosening the two screws above the temp display. On the left hand side there is a black circular ish shaped item. This is the divertor motor. This has a block shaped plug attached on one side. Pull this off. To remove from boiler there is a retaining clip which slips in from the left hand side. Pull this off and then you can remove the divertor. To replace this will cost approx £30. You just push it in where you took the old one out. Put clip back on re attach block plug. Put back together and hopefully hey presto heating works again.
Well it worked on mine.
Andy G, January 2007
