The Radio Teleswitch Service (RTS) is being phased out gradually rather than being suddenly discontinued overnight, after the UK government stepped in at the last minute. However, it remains unclear which customers will be the first to be affected, with around 100,000 of the devices still thought to be active in Scotland alone.

Advice Direct Scotland, which runs the national energy advice service energyadvice.scot, criticised the lack of clarity from regulator Ofgem which is leaving consumers in the dark.

Introduced in the 1980s, RTS meters use outdated longwave radio signals to switch between peak and off-peak rates.

Unless the meters are replaced, customers risk losing control of their heating or hot water or being moved onto a more expensive single-rate tariff.

Under the latest plan, the first part of the RTS switch-off is only supposed to affect a “very small number of homes and businesses in carefully targeted local areas”. Affected customers should be contacted by their suppliers in advance, with local teams able to respond rapidly if households experience heating and hot water issues. However, there has been no clarity about which parts of the country will be affected first, or whether vulnerable households are being prioritised over others.

Advice Direct Scotland has been calling for a dedicated remediation fund, backed by the energy industry, to be set up for customers who face additional costs or disruption. In one example highlighted by the charity, a 69-year-old from Wishaw in North Lanarkshire had to spend £700 fixing her kitchen after being forced to install a smart meter.

Anyone concerned that they might be affected by the RTS phase-out should contact their supplier. Support is also available at energyadvice.scot or by calling 0808 196 8660.

Andrew Bartlett, chief executive of Advice Direct Scotland, said: “Given that there are still around 100,000 RTS meters in Scotland, a mass switch-off of the signal today would have been nothing short of a disaster.

“While it is welcome that ministers stepped in and ensured a phased approach instead, customers are still being left in the dark about who will be affected first. The whole process has been sorely lacking in transparency, and there is still a lot of unnecessary confusion and uncertainty about how this gradual switch-off is going to work.

“As well as more clarity, we would like to see a commitment to an industry-backed remediation fund, ensuring that nobody is left out of pocket for replacing their meter.

“The most important thing to remember is that free help and advice is available. Anyone who is worried should visit www.energyadvice.scot or call 0808 196 8660 for assistance.”