Scottish Power Bill / NSC

Coates_2

Hi all, i came on here a wee while ago and took plenty of advice, unfortunately i need some more now, i just received my bill (another estimate it says) but it has me oweing £36 to scottish power, they have though reduced my direct debit by £3 a month, why is it reduced when i owe more than i paid? how can they be so accurate with estimates?
i don't really understand it, it's terribly confusing!

Also i went to their website to sign up online, i'd rather input my actual figures and pay up in full than risk estimates, only it's asking what option i want to choose and there are some with 'no standing charge' available, the so called etimate on the back says i used 524 units of gas and 2525 units of electricity in the last 6 months, the standing charges add up to £44.46 - would i benefit from going on a plan that didn't have them?
I can't decide which would be best for my household but i know i have to sort it out so any advice would be greatly appreciated.

Also it may be important to note that we will only be in this house until July 2009 so the discount option stating cheaper fuel till then might be worth a shot?
Many thanks
Coates

Fixed Price Energy online Look forward to the security of fixed prices until 28th February 2011 with our Fixed Price Energy offer. You will have no more paper bills and a discount for managing your account online.
Fixed Price Energy online NSC Look forward to the security of fixed prices until 28th February 2011 with our Fixed Price Energy offer. You will have no more paper bills, a discount for managing your account online and our No Standing Charge option means that no daily service charge is applied to your fuel charges.
Discounted Energy online NSC Our Discounted Energy Offer is guaranteed to remain 3% below our standard monthly Direct Debit prices until July 2009. You'll have no more paper bills, a discount for managing your account online and our No Standing Charge option means that no daily service charge is applied to your fuel charges.
Online Energy Saver 4 Switch to Online Energy Saver 4 to receive our cheapest available prices. You will also have no more paper bills and a discount for managing your account online.
Online Saver 4 Green Fund Help the environment by donating to the ScottishPower Green Energy Trust. You will have no more paper bills and a discount for managing your account online.
Online Energy - Standard Manage your energy exclusively online and put yourself in control. You'll also have no more paper bills and a discount for managing your account online.
Online Energy - Green Fund Help the environment by donating your combined Gas & Electricity Offer discount to the ScottishPower Green Energy Trust. You will have no more paper bills and a discount for managing your account online.
Online Energy - Standard (No Standing Charge) Manage your energy exclusively online and put yourself in control. You'll have no more paper bills, a discount for managing your account online and no daily service charge applied to your fuel charges.