Smart meters are supposed to make paying our energy bills easier and cheaper. But is that the whole story? In 2011, the coalition government set out plans to get smart meters into every home and said it could complete the rollout by 2019. But years later, only two-thirds of homes have one, and millions of smart meters don't work as they should. Zoe Conway investigates why there are so many problems that leave customers frustrated and out of pocket – and reveals how well your smart meter works can depend on where you live.