Re: Fuel Direct scheme to pay bills.
Fuel direct payments cover the cost of the fuel used and something towards clearing any arrears.
The DWP don't set the amount taken for current use. Scottish Power will let them know how much they need to cover a year's worth of use based on previous bills. The DWP will then divide this by 52 to work out the weekly payment. If the amount Scottish Power ask for is higher than your benefit or would leave you little money to live on then the DWP will not agree to the deductions being made.
The DWP do have a limit to how much can be paid on a weekly basis for the arrears but I couldn't find anything that said what the maximum currently is. It's usually only a few pounds.
So if you have arrears and are paying quite a bit every month to clear these then it is likely that you will save money by changing to fuel direct but if your repayment level is low then you may not.
The only way it will help current fuel costs is if your supplier switches you to a lower tariff because you are paying by fuel direct.