The suppliers make very little profit as it is. It's a few pounds per customer. The cost of the price cap amount of energy for the average user is predicted to go up to around £4500 next April, following yesterday's shortening of the 2 year price protection.
There's no one solution, but lots of things that can be done that, when combined, will make a big difference.
A further universal bill credit, like the £400.
Extra payments for people above pension age or on UC/TC/DLA/PIP which would hopefully capture all lower income households and those with additional needs in the most cost effective way.
Tiered pricing on above average use and incentives to reduce energy consumption, eg get a £50 bill credit it you use 10% less than last year or similar.
A windfall tax on the producers, who are the ones making all the profit, not the suppliers that end users buy their energy from.
Mandated energy saving measures like requiring businesses to keep their doors closed if they're using heating or air conditioning, lights when unoccupied, that sort of thing. The main reason why prices have gone up is that demand exceeds supply, so the balance needs to be shifted by reducing demand.
Freely available advice and subsidised surveys so people can find out what the best way is to improve the energy efficiency of their homes.
Enforced rules to improve energy efficiency measures in rented homes.
Proper subsidies to help people and small to medium businesses invest in energy saving measures so they can fit solar panels, new windows etc without having to shell out thousands and face decade long payback periods.
Extra sales taxes on 'luxury' energy hungry appliances like hot tubs, like you pay more road tax if you run a car that uses more fuel.