I recieved a 12% Direct Debit Discount, an 11% Pay on Time discount & a $25 credt on my last bill, but no matter how I crunch the numbers I cannot work out how this is calulated. I understand that the discount doesn't apply to fixed charges, but excluding them I still can't get to the 11% or 12% figures. Complicating my calculations further is the solar feed in tarrif I recieve & i don't know if that forsm part of the calculation or not. By my calculations the discount on the usage charges calcu ...