A labor showdown crippled Irish Ferries for a fourth straight day Monday, as company officials and union leaders refused to budge from their demands, presented in rival plans to independent mediators, according to an AP report. In dispute is the company's widely condemned plan to pay off 543 unionized workers from its key Britain-Ireland routes and replace them with Eastern European workers at much lower wages. None of Irish Ferries' four vessels tried to sail Monday, partly because Ireland's largest labor union - the Services, Industrial, Professional and Technical Union, known as SIPTU - warned that their members would refuse to let any of the company's vessels dock, according to the report.