When we get a bill that run a few pages long, we tend to check the main numbers and not the details unless there is a big change from month to month.
It happened to me with my Cell Phone bill until I noticed a suspicious charge last month for something we did not order.
The new invoice that I just received included the same charge so I reviewed 10 months worth of undue charges. It is always the same amount $10. Multiply this by 10 and someone has been making around $100 off my back.
I called at&t (my wireless provider), and they credited me for 3 months of undue charges. I still had to call Mqube now part of Verisign to ask them to stop any future billing and find out the origin of the $10 charge.
They did not know offhand but told me they would find out.
So a word of advice, when you get your cell phone bill, scan it for suspicious charges.
It could save you enough money for a good meal out.