Should a gas boiler and hot water cylinder be drawing 8-9 kwh per day?

I have a gas boiler and water cylinder (unvented). Hot water and heating controlled by Honeywell device. Boiler recently serviced. For some time (ie 1+years) I have noticed high electricity usage, even when the boiler is switched off and hot water and heating is switched off at the controller. When away recently I switched everything off but the fridge, smoke detectors and boiler at the electricity meter and usage was still 10 units a day at the electricity meter - when in the house with water heated daily but no heating on, our electricity usage is 11-12 units daily. When away last week I then switched off the boiler/heating system at the Consumer Unit and usage went down to 1.5 units of electricity daily. So it appears the boiler/cylinder is drawing around 8/9kwh each day, even when switched off. Question - is it normal when the gas boiler is off, and heating and hot water are switched off at the controller, and the immersion switch for the cylinder is off permanently, for the system to be drawing betweek 8-9 kwh of electricity each day? If not, what might be the problem? Thanks.