Stella, please re-read her post.  I don't think you read it thoroughly.  It happens to me all the time.  In my case it's related to something called "velhice".

We can be charged for a service or a product (goods, supplies, etc.), but not for a bill.  We get something and we are charged for it, right?  But a bill is merely a written statement that shows how much we owe and for what, right?  When we pay a bill, we are not paying for it.  (In other words, we are not paying someone so that they will let us become the owners of the piece of paper.)  No, we are paying for whatever service or good that the bill represents.  When we pay a bill, we pay it.  In English there is a big difference between "paying for something" and "paying something".  We pay for a house, but we pay the mortage that represents the price of the house.  We pay for a car, but we pay the car loan that provided us with the money to give to the seller of the car for the car. 

"Accounts payable" refers to accounts with customers to whom we owe money.  "Accounts receivable" refers to accounts with customers who owe us money.