in July, I had 7500 rollover minutes, but 6500 expired - and I didn't read my bill! August bill jumped from $60 to $250, and I've already done more damage than that for next months bill!!!

BUT, the nice people at Cingular actually credited back all the overage charges (there was no chance at getting the expired minutes back - it just doesn't happen, and they properly expired). They even gave me a small amount of bonus minutes to tide me over for the next couple of days, until next months billing period ends (and then I'm back to using free plan minutes).

Moral of the story: READ & UNDERSTAND YOUR CELL PHONE BILL!
And for Cingular subscribers: *646# (then call it), will not charge you a minute of airtime, and will generate a free text message that will show your current minute usage... This entry is now stored in my phone with no name, so that it is the first number in my directory.