Four in five people pay a significantly higher price to at least one of their providers for remaining with them.
The overcharges apply across the five essential consumer markets of mobile, broadband, home insurance, mortgages and savings.
A super complaint has been lodged with the competition watchdog, but what can you do now to save money on bills?
In the first instance, Citizens Advice suggest to look at your recent bill to see if you are being penalised.
Changing suppliers or providers for the first time can typically lead to savings of up to 20%.
Use price comparison websites
Change to a monthly direct debit
Setting up a monthly direct debit can save you money but it is important to make sure companies sets it accurately so you are not overcharged.
Change to an email bill
Switching to an internet tariff can save up to 10% with the only change being a bill sent over email rather than through the letterbox.
Research government grants
There is a range of government initiatives designed to improve heating and insulation in your home.