MX 20 -another faulty display

2 years ago we were forced to replace (for $600) our MX20 display
because it had vertical lines. At the time, we were led to believe
these were "growing pains" and that what is now Garmin AT had
re-designed the MX20 box so display failures would be less common. The
new displays even came with an 18 month guarantee. (wow)

As you may have guessed, ours has failed again, despite the "new"
design. We also have a special avionics fan back there to help with
cooling. The Garmin AT rep now says this isn't a heating problem and
isn't really a problem at all. According to him, the displays are only
expected to last about 18 months.

Anyone else have this problem? The rep says all the larger aircraft do
and that this is just part of maintenance, sort of like changing your
oil (my interpretation). Too bad these delicate displays are about the
best on the market (for their size) otherwise I'd love to get rid of it.