Thousands of consumers may have been overcharged due to confusion where customers with old imperial gas meters had been registered as having a new metric meter and vice versa.
This mistake meant that the conversion factor of 2.83 between cubic feet (imperial gas meters) and cubic metres (new metric gas meters) had been wrongly applied, or not applied at all, resulting in over and under charging.
Ofgem has written an open letter to all gas suppliers requesting that they respond outlining how they will identify affected meters and provide consumer redress.
A spokesperson for the regulator said: “Ofgem is aware that a very small number of gas customers are being incorrectly charged for their energy use and has taken fast action. Working with Energy UK, we’re ensuring suppliers take immediate and decisive action to identify affected customers.
“Ofgem is working with suppliers to ensure consumers don’t lose out. This includes suppliers setting out plans to redress their affected customers, and to reach a quick resolution.”
Big six supplier Eon has identified around 350 of its domestic and small and medium sized business customers to be refunded in full. The firm will also ensure they are “appropriately compensated”.
A further 250 current customers have been undercharged as a result of the mistake but will not be required to pay anything. Eon is undertaking urgent work to establish whether any former customers have been affected.
Energy UK is working with industry to address the issue and said: “So far, detailed analysis shows an extremely small number of accounts have been affected, so customers need not worry.
“Any customer affected will be contacted shortly by their supplier and where there has been overcharging, a refund will be issued as quickly as possible.”