Defective 2 of 3 copies after 4 weeks

Actually quite a good machine, however, was like many other defective after 3 weeks with me is one of two copies ordered. There was no error message, the desired comfort Chill was also displayed, but the radiator was in automatic mode, unfortunately cold.

Addendum 1: Also supplied by Amazon as a replacement copy was already again broken after 4 weeks; neither hot nor in manual in automatic mode.
Update 2: And also the last remaining copy now works with me (01.04.2014) no longer properly: The heater is only lukewarm, even taking the thermostat to 25 degrees.