is EA liable if one of there IT techs screws up my computer

Employers are liable for their employees' torts committed during the course, and within the scope, of their employment.  If EA's techician was negligent and screwed up your computer during the course of his/her work for EA, EA would be liable for the damages you suffered as a result.  However, you should check your agreement with EA to see if there is any limitation on liability.  Contracts like that often say something along the lines of "your recovery for any negligence of our personnel is limited to $50", and these clauses are often enforceable unless you can prove that the technician was more than just negligent.