They usually average your electricity bill, before Hari Raya's, Dewali ( Deepavali), Christmas, New Year, Lunar New Year. Then certain months, they take meter readings, usually their average is higher than you use & for 3 months, they would collected more than usual from you & 'they adjust' what they had taken, in comparison to your usage. Then they average the bill again....
If you use GIRO, you have already "top up"...Stink Power cash account..."HUAT"! ah!... that is why GIRO in Chinese is 才路, their 才路, not yours. Anyway, your money is your own hand, take care of it..if possible, cancel all 才路, theirs of course!!