Disgruntled - No Home Internet Access

I haven't had Internet access at home since Thursday.

ATT - SBC Global can't seem to fix the problem. Apparently, based on my calls with customer service, another carrier has taken over our line and ATT is saying it can't do anything about it unless we ask the other carrier to come off the line. But, the problem is we do not really know who or what that other carrier is nor do we have any contact info.

I also find it weird since we are subscribed to ATT, have never asked the company to deactivate our account, and have never missed any monthly bills/dues.