3 phase electricity supply

lohr500

I think you need to start with the assumption that the meter is reasonably accurate and figure out what is causing the high reading.

Firstly, are their any adjacent workshops/houses/businesses near your property that are not owned by you?

Secondly, could you post photos of the consumer unit or units (fuse boxes) . Are the individual breakers labelled with what circuits they control? 

Try the basic sanity test of switching off all the consumer units in your property and check to see if the meter reading keeps increasing. If there are adjacent properties or workshops, do this test on a working day.
 
If the meter stops increasing with all your consumer units switched off, then you can start to look at the individual circuits. Switch all the individual breakers off in the consumer unit/s and then switch each one back on in turn whilst looking at the meter. According to the instruction manual posted earlier by QrizB and subsequently Keep_pedalling,  the meter has a flashing red LED which flashes at a rate of 500 flashes per kW/h. So the faster the LED flashes, the greater the consumption. 

Other basics :

• How much electricity are you actually using?
• How big is your house and what sort of heating and hot water systems do you have?
• Do you have any devices that would use a lot of electricity such as a swimming pool, hot tub, electric AGA, large tropical fish tank, hot air blowers, etc? 

Going through the above tests and questions should help to determine if the usage is by and large correct, or if the meter is indeed faulty.

As Nextporter mentioned you could also either buy a clamp meter to test the current on each of the three phases or get a competent electrician to do so, which would also give a sense check on the meter accuracy.
A cheap one would cost around £15 from Amazon. Might not be 100% accurate but good enough to give an indication of the amount of current flowing through each phase. Especially useful if one of the phases is drawing considerably higher current than the others as this will help to start narrowing down the high usage.

lohr500

@DrH2 Any update on the feedback provided so far from those who replied?