Mistakes can still happen in calculating a monthly bill.
Sometimes there is a problem with the electrical meter itself. PRECorp staff will personally investigate when the previous accurate reading was recorded, then the bill is pro-rated accordingly.
Other times the reporting device is inaccurate, not the meter. In this case, the meter reader will read the meter personally and billing clerks will adjust the daily use accordingly.
If the mistake favors PRECorp, the company only goes back six months. If the mistake favors the member, PRECorp will go back to the date the mistake first occurred.