GREENSBORO, NC -- Past due. At some point, we've all missed a payment and received a letter like that.

But according to Duke Energy, The International Civil Rights Center and Museum got 23 past due notices. Let me give you a closer look at the paperwork filed with the state between the Sit-In Movement which operates the ICRCM and Duke Energy.

Because of the past due notices, 23 of them between October 2012 and January 2017, Duke Energy added an $18,224 deposit to the museum's bill.

The Sit-In Movement doesn't believe they should be required to pay it. How did Duke Energy come up with that amount and why? Actually, this deposit issue comes up with everyday 2 Wants To Know viewers too.

If you have three non-pay disconnect notices in a 12-month period, Duke Energy automatically adds the deposit charge. The deposit charge amount will be different for every customer. According to Duke Energy - it's equal to two-twelfths of the bill.

So, is this legal? Yes. The North Carolina Utilities Commission lets companies do this. And Duke Energy spells it out in the fine print of your bill.