i'd call them or go to the local att store... don't go to a parrot go to the real stores and talk to someone.. they will help.. this happened to me too[not this extreme] good luck.. let us know because 700$ is just insane
You don't even need to go to the store. Just call customer service and they can correct it. I have had similar issues with ATT. They put add-ons on my account, etc - once I called they fixed it.
Side note ~ the add-ons like roadside assistance, insurance, etc where done at the Store, because the sales people at the store get commission on what they add on. So, if I were you I would call customer service. This was explained to be by ATT customer service, yes it isn't right, but it happens!
The fact that it's "chargeback" makes me think it might be for 2 months usage. But still, that's $350 a month and unless you've got more phone lines then it shouldn't be that much, unless you went waaaay over on minutes. Good luck with resolving. I've always had pretty good luck with AT&T customer service.