Customers of major energy firms including British Gas, EON and EDF are being issued a warning over putting their heating back on this summer.

It’s been a cold and miserable summer so far with barely any hot weather to write home about. And some people have even noticed their boiler automatically turning back on overnight due to the cold conditions – and even frost – we’ve been battling this June.

But if you do turn your heating back on, you could end up facing a nasty shock, according to…