The current expense has next to nothing to do with privitisation which should be evident from the huge number of private suppliers who are going out of business. Clearly they're not creaming off huge profits. Even in the good times Bulb et al didn't actually make money. They've effectively been subsidising their customers' bills with their investors' money.
I agree that there are structural issues on the generation side and privitisation there will have contributed but let's not pretend that utopia lies in nationalising all public services. Nationalisation tends to lead to under investment and unions who like to throw their weight around. The happy medium for energy is probably a highly regulated, privately run industry which I think is what we've tried to create in this country. We've just done it very badly.