Programmer fault or boiler?

Hi,

We have just moved in a house which has been vacant for about two years. There is an Ideal Classic FF350 boiler within an open vent system controlled by a British gas UP1 programmer. We've tried to program/use the Hot Water Advance function but the boiler also triggers the CH despite the CH controls being off. We've had to use the immersion switch on and off, which is far from being economical and impractical... Sorry it might be nothing but we've always had combis and this systems is new to me...
Is this normal after long period of inactivity or could there be a fault?

Many thanks.