Anna if you go on a direct debit system (i'm iwth Tru Energy and it's called an easyway payment plan) with your electricity provider they will take money out of your account fortnightly and you won't ever have to pay the balance of the bill even if it's not in credit. What they do is average your bills out and come up with a fortnightly amount which would cover your energy usage. Doing it this way also means you get the discount for paying on time.