I know it's no consolation, but I'm now on my 3rd LNB. The first one didn't show any symptoms until after the installer left (and the symptoms actually mimicked a bad receiver, and I was without that receiver the whole time). I then had to wait a week for an appointment on a brand new install, and the guy spent over an hour trying to nail down the problem to the LNB. However, the one he replaced it with had an issue that didn't present itself until the temperature approached zero a few weeks ago. As the temp dropped, it would start dropping signal momentarily. The lower it went, the more often it dropped. One night it went completely out for hours when the temp hit -15. It took two calls to the center to get an appointment (the first rep said they'd never heard about the problem, and since the system tested OK they couldn't roll a truck, the second rep said they knew all about it and made the appointment with no problems), and again the first available appointment was a week out. Of course when he got here the temp was 65, so there was no chance that the problem would present itself.
It sucks to live with the problem, but when you think about it, how long will it take to ship you an LNB or whatever part is bad to install it yourself (because you can't just go to a store and pick one up)? In most cases, the answer is 5 business days.. So it's a wash.