Fraud department not responding

The number for the fraud department is not answered and gives a message to open a fraud claim online. I did that in September and still no one has contacted me. I've spoken to numerous att representatives who all tell me fraud will contact me but they don't. I have now been billed over $1100.00 dollars for a phone I did not order or authorize or receive. I have been reporting this since September and nothing has been done to help me. I have a fraud claim number but literally can't reach anyone and for months no one has contacted me. I have been with att for yeara and have never experienced service like this. This is the worst customer service imaginable.