Over 820,000 households could see their energy bills increase when a major service closes down next year.
These households have electricity meters that rely on the Radio Teleswitch Service (RTS) to set the rate of energy - this will charge them cheaper rates depending on the time of day.
The devices, such as Economy 7 and other multi-rate energy tariffs, pick up the different energy rates through the RTS signal - this is broadcast alongside the long-wave channel for BBC Radio 4.
