Check your home AT&T bill for services for voicemail or email that are form a company other than AT&T. The usual culprits are "ESBI" or "Residential Email."
Usually they are only $12.00 -$15.00 each so you might miss them, but they will claim you signed up for monthly service.
They will cancel and promise a credit --but you must insist that ATT give you a temporary credit right now on the bill. Then ask ATT to "BLOCK all third party charges to your account."
There. I feel better.