Its one of the things that OFGEN should be looking at with some urgency. For years, consumer rights organisations - like Which! - have been campaigning for simpler, more transparent energy bills, together with a much reduced number of price tariffs.
There is more than a suspicion that utility companies want to keep the status quo precisely because it leaves the consumer confused and therefore reluctant to consider changing, especially to another company.
There were some positive signs emanating from OfGem - but really, they should have done something long before now.
This would be EDF energy, emmie? I suggest telling them that you simply want the cheapest tariff for your useage requirements, taking into account the size of your property and the pattern by which you make use of the energy - things like if you are attempting to run dishwashers and do laundry during the night, that kind of thing.