British Gas customers, as well as those with EON, EDF and Octopus Energy or OVO are being told they have just 30 days to slash more than £640 off their energy bills.

Energy price regulator Ofgem, which sets the price of gas and electricity for UK households, recently announced a price cap change coming into effect on July 1.

This cap will reduce bills by an average of £122, but the catch is that it only applies to the standard variable tariff, i.e. those who are not currently on a fix.

And…