Hi Jim,
I'll do my best, but British Gas bills online are incredibly difficult to read. They overwrite previous bills, and since I owed them some money from trying to get my account sorted it looks like they back date all statements to the start of that repayment period.
Looking at my current bill, they say I've used about £180 worth of Electric between 24 July last year and 8th Feb this year. Not sure I believe them to be honest, and that I still owe them an extra £70 from previous usage.
I never take my storage heaters beyond half or 2/3s on the input dial. However, I go to the gym a fair bit, which I reckon keeps my metabolism going, keeping me warmer than more sedentary people (doesn't mean that I'm right though ;) ). Also, since storage heaters are reactive, if there's a cold day or two, I tend not to turn it up, unless it gets REALLY cold. I also live in a 2 bed flat, but live on my own, which means the spare room heater never gets used at all. If you're you're sharing with flat mate then this could be increasing your costs, if their heater is on max all the time.
Another thing that occurs to me is that the heaters you have are really old and not that efficient? Mine are around 7-10 years old. I've thought about replacing them, but they cost around £200-300 apiece, and let's face it, I'd need to be able to save a LOT of cash on a monthly basis for that outlay to ever become economical.
Hope that helps, and sorry for the delayed answer.
Chris