The German trade union verdi is extending its strikes ahead of the fourth round of negotiations in the wage dispute at Deutsche Bank subsidiary Postbank. On Thursday, in addition to employees in the back-office service units and call centres, verdi is also calling for work stoppages at branches throughout Germany. “This will once again send a clear signal that all employees are behind the demands for a significant improvement in pay and an extension of protection against dismissal,” verdi negotiator Jan Duscheck said on Tuesday in Berlin. Strikes have already been taking place in the back offi…