How bad can a Sky HD Box be?

In 4 weeks, I am now on my fourth Sky HD box... and the refurbished one that has been installed today needs to be replaced because it does not recognize the telephone line.
I am so fed up with Sky, their support and their unreliable HD Boxes.
It is just unbelievable: 4 boxes died in 4 weeks. They obviously sub-contract the replacement of the boxes to another company, and the poor guys are given refurbished boxes that are not working well. Last time, the engineer brought a box to replace the faulty one. This box did not receive satellite signals, so he had to fetch another one from the van.... Oh dear.
How bad can it be?

Ultimatum: if my current box fails again, I am moving to Virgin Media!