What is wrong with my navigation system?

Good morning, My navigation  unit in my car start
showing DVD disc reading error please consult your
dealer. I was still able to use the touch screen to
control my FM and XM radio stations. I bought my car
to the acura dealership  for scheduled maintenance
and to check the DVD unit..The service person called
back and said it needed to be repaired / replaced and
a list of other problems my car was starting to have.  
When I went to pick up my , the error I was receiving
for my navigation unit went to "downloading
software" then check disc.  Now, I'm unable to use the
touch screen to control my radio stations.  Before I
left, i reported the issue to someone because the
service person who handle my car was gone for the
day. Eventually,  2 service consultants and the service
manager came to help and told me the guy who did
the work on my car mentioned that was the only error
that showed for him! I went back and forth with them
which was worthless because they believed the guy
who did the work on my car .. I apologize  for the
length..Can someone explain how I've been receiving
one message for weeks then magically  after a
dealership visit a new message appears  and now I
can't work the touch screen?? Oh and clock has the
wrong time now to .. Before, it was the correct time..