I will report my expierence with xerox telephone support.
Today I called the support. They told me - before asking anything to the problem!! - a technican must come to me and it cost me at minimum 400 € plus taxes. This is nearly the price of a new WorkCentre!
The Product is 1 year and 3 month old. The guarantee is left since 3 month. And now it is only a brand new brick of waste!