Continued Unresolved Speed Issues

For over 2 months I've been complaining about not getting the speeds associated with my premium plan (27/7).  Technicians have been onsite and cannot find anything in the wiring or the setup.  One technician informed me that a supervisor told him that it was a "card in one of the nodes".  As of yet there has not been any change in speeds.  What do I need to do to get this matter resolved?  I'm paying for service that I'm not getting and right now FRUSTRATED IS AN UNDERSTATEMENT.

Thanks,

James