If the price cap is based on the total amount paid by an average user, then does that mean that if we all make a big effort to use less in the hope of having lower bills, the capped unit costs could actually rise as a consequence?
I honestly think that, however much we reduce our usage, we'll see no difference in what we end up paying. I'm not convinced that they start from the value of a single unit and go from there - I really think that they know how much profit they want to make, divide it by the number of consumers and then base the nominal price per unit on that.
If we all cut our usage in half tomorrow, they'd just increase standing charges even more - and quite probably the unit cost too, likely giving the excuse that they need a certain amount in to maintain the whole infrastructure and supply chain - and blaming us for trying to deprive them of their necessary income by using less!
Say a private company runs buses and has a certain required income for each bus per day, and then half of their regular users stop using it for whatever reason, do we really think they'd keep the prices the same and sustain a 'loss' (whether that 'loss' means not breaking even or not making what they consider an acceptably high level of profit)? Of course they would double the prices for those still using it, and then double them again if that forced another 50% of people to stop using it, until the remaining people who have absolutely no choice but to keep using them end up paying buttock-clenchingly outrageous prices. Yes, they can make some economies, such as gradually replacing their buses with smaller buses - but they still need a driver for each one and maintenance and admin staff costs would stay relatively static.
Remember when we used to have horribly inefficient kitchen appliances, light bulbs, boilers, cars etc. - compared with the ones we have today? We were urged to upgrade each time new technology was released, and told of the fortunes we would save. Didn't really happen, did it? The energy companies never intended to make less money from us at all; they just wanted us to use less and less of their product whilst paying them an ever higher total amount for it.