Maths backwards

They've discovered a new problem with Sewerage and Water Boards fancy billing software.  It doesn't work in reverse.

It turns out that in tens of thousands of cases, the agency may have shortchanged the refund amounts.

More than 26,000 customers have received at least one bill that shows negative water usage since October 2016, the S&WB's way of correcting a previous bill that charged customer for more water than they actually used.

But the process of correctly crediting those accounts, which requires S&WB employees to manually calculate the amount owed, has left many of those customers still owed money.

That’s because while the S&WB charges for water at two different rates, depending on how much is used, it provided credits only at the lower rate in many cases.

Utility officials say they are taking several measures to address the problem. They are working to calculate the correct amount the agency owes customers and issue additional refunds. They have asked Cogsdale, the company that supplied the billing software the utility uses, to fix the bug that is at least partially responsible for the problem, something that should prevent new issues from arising and that should be complete in the coming week. And they have asked the city's Office of Inspector General to investigate.

Is that really a "bug," though?  Looks like the Advocate made a working rebate calculator for their webpage and I'm pretty sure the most tech-savvy person over there is, like James Gill or somebody.