I just discovered on my AT&T bill that they had added up a large number of small amounts and came up with a result that was too high by $7.98.  12 months of this would be almost $100!  And if this is a gliche in their bill-generating program or a deliberate deception which affects many, it could easily be a huge revenue source for AT&T that probably goes unnoticed by most customers.  That was on a bill of about $54.  Just last week I was working on the AT&T bill for a non-profit for which I'm treasurer.  The bill had gone from around $50 a month to a current bill slightly over $300.  Customer service helped me determine that we had been incorrectly charged for early termination fees when a plan had been changed within the grace period.  By the time all of the erroneous charges had been removed, the bill was down to less than $5!  Considering the huge customer base for AT&T, one can only imagine how much $$$ is being incorrectly collected by AT&T!