benten

how do you work out how much per day an economy 7 boiler uses if the timer is knackered and it is permanently on ? my electric bill was high but working out 7 hours @ 20p and 17 hours at45p dosnt tally up to the bill . is there a way to work it out so i can claim back overpayment due to a faulty timer/boiler from my landlord ? many thanks