Without seeing your bill I'm assuming you're getting your bill quarterly. I'm with eON with their online service - they email me and I put our meter readings in myself before our bill is cut, but we pay by monthly direct debit. Are you paying your bill in full monthly or quarterly or do you just pay by direct debit each month? You pay x amount set up between you and the provider and they use that to cover your usage each quarter - its kind of complicated to explain it and this may be how you're paying if you're having difficulty reading your bill. Its done this way so you're paying the same amount all year round, but usually use more electricity & gas in winter, but its kind of like putting your money in "savings" with your provider to cover your winter bills - it ends up equalising itself in the end.
Usually every provider lists their prices per quarter (even if you pay monthly). You pay one rate for the first so many kWh, then the price is lower once you go over that quarterly limit. I'm looking at my eON bill and its quite easy to read, but then kWh's make no sense to me. I just go by usage. If you're using a lot of high energy items in your house or not switching items to standby your bill will go up... On your bill it'll also give your meter number (you'll be able to see it on a little plaque) - you may want to just double check that they're giving quotes for your meter & not your neighbor's. (When we first moved into our house and switched from British Gas to Powergen they ended up switching our neighbor's power over, but were sending the bill to us and the only way they found out was when I read the meter # out to them once I closed account with them. But we've since gone back to them and are happy with them, but need to reassess our bill just to make sure we're getting the best deal for us.)
Have you checked to see if your property is Economy 7 (different rates for daytime from evenings)? This may also make your bill harder to read.
We tried Scottish Power, but their prices just got to be outrageous because they quote you their rate, but conveniently forget to mention their daily surcharge for the privledge of being their customer.
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If you look at your bills they'll tell you what your starting meter reading was and your closing meter reading for x amount of time. If you're billed quarterly just split your bill into thirds to get an average monthly usage. You'll also want to figure in how much you pay each month as well... Then you'll probably want to check with sites such as uSwitch.com or Money Saving Expert, Which? etc. just to see if another provider would be cheaper.
Sorry for the long rambling post. If you need me to clarify just let me know.
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