Three years ago, the Haggler’s credit card bill seemed to stop showing up in the mail. Another month went by  no bill. The month after that, still nothing. Each month, the Haggler would call the issuer, Bank of America, and pay over the phone, then ask the same question: "Why did you stop sending me a bill?"

We’re still sending you a bill, came the company’s reply each time.

Guess what? The company was right. It just was sending the bill in a restyled envelope, with no trace of “Bank of America." In other words, it looked like junk mail, and the Haggler kept throwing it away.

Now, the Haggler can’t prove it, but this seemed like a brilliant, low-cost way to pocket a fortune in late fees.

“We are not trying to fool people, and we don’t change our envelopes on a regular basis,” said Anne Pace, a company spokeswoman. She explained that the change in envelope design was prompted by the 2006 acquisition of several credit card companies, after which the envelopes of all customers were left blank “for the sake of consistency.”