Millions of households are at risk of paying more than their usual energy bills, a charity has warned.
More than half of the homes in Great Britain are now equipped with it smart meters which automatically tracks energy consumption throughout the day, so you get a more accurate bill at the end of the month.
But Citizen's Advice has warned about this catch up on bills become a problem, with disruptions and slow service resulting in automatic measurements not being carried out for a long time.
This could mean that households pay too little until the automatic measurements catch up. Bills of £1,000 and more have been sent to customers after the so-called catch-up bills arrived.
One in five households with a smart meter – or 2.86 million homes – still have to manually report meter readings on a regular basis because their device does not do this automatically, according to research by the charity.
Nearly a third are also experiencing problems with the in-home display (IHD) screen that allows households to track their energy use and costs.
Suppliers can currently back up accounts for a year, which could amount to thousands for some households. Citizens Advice said this period should be reduced to six months to avoid high catch-up bills.
A quarter of people who asked the charity for help with smart meter problems had problems with billing.
The charity now wants new rules that will force providers to identify and resolve problems as quickly as possible.
Citizens Advice wants to close the so-called 'responsibility gap' between suppliers and the data communications company, so that all problems can be diagnosed in a timely manner.
Citizens Advice chief executive Dame Clare Moriarty said: “The whole point of smart meters is to enable households to save energy and money, but in reality millions of people are missing out on these benefits due to problems with the technology and poor service from suppliers.
“Energy companies really want customers to get a smart meter, but when problems arise, they are often nowhere to be seen. That has to change.
“Suppliers have been far too slow in solving problems with problem meters. New obligations and stronger accountability measures are needed to restore public confidence in this essential tool to achieve net zero.”