Mr Miliband said: "These are people who are overcharging people and so of course they are going to say when someone calls time on it they are not very happy.
"I've written to them today to say, 'Look, come on, make yourself part of the solution not the part of the problem.'
"I am determined to stand up to the energy companies, to get a fair deal for consumers and also get the investment that this country needs."
As Ed Miliband clashes with the energy giants on prices, it is worth knowing how your expensive energy bills are actually made up.
A leading competition lawyer says an energy price freeze could leave Labour open to challenges from the courts or the European Commission.
Whether or not you approve of a state intervention into industry, there are at least two big potential obstacles for an energy price freeze.