Can not access email, webhosting or voicemail control panels

I have been attempting to access our "company domain" control panels for: access email, webhosting or voicemail to make some simple changes. Have not been able to use past user names or passwords to do so. Can not establish new ones. Can not do anything but log into a useless "comcastbiz.net" account created by Comcast for some unknown reason. We are called a "legacy account" because we have been with them for so long. But maybe not much longer. Can not get tier 3 at national level to resolve. Been a Buisness Class customer for 9 years. Have never seen anything this bad. 1&1, Godaddy, Network Solutions, Apple, MicroSoft and others run circles around Comcast. Still waiting for a resolution after 2 weeks of nothing but long phone calls yeilding no results. It would be great to get some results so we can just do the simple com stuff needed to run our business.