Hilfarion: However, the power bills we've been getting a insanely high, and the multiplyer is the only factory that could be wrong - for example, the metre says we've used 45 units over the weekend (when the building was closed)...
That meter is so old there is no information on the web about it.
How long has your power company been applying this multiplier? Surely you would have noticed before now if your bills were far higher than what you had been expecting due to the multiplier?
If you have a load which you roughly know the wattage of - turn everything else off - then turn on that load for exactly an hour and see what the difference in the meter is. It should be fairly easy to get a good idea of multiplier (or not) from there if the load is constant. A lighting load might be the best for that. Take before and after photos and paste them up here.
There are a few EE people posting on this forum but it may take a day or so before they log in and see this topic. It may pay to hang fire in case they have something to add.