What is AT&T Corporate Headqarters phone number in Dallas Texas?I am looking to speak to Randall L. Stephenson?

My parents have been fighting extra charges added to our AT&T bill. The have been adding amounts to our bill for services that we do not have. My parents have been trying to get this issue cleared up for over a year. Just yesterday they randomly turned off our internet. My dad called and had it turned back on. Then today they are randomly turned off our home phone. My brother is in Iraq and the internet is our only access to him, and they do not have the right to take that away. This is getting extremely ridiculous. If anyone has the number, please respond.