I have a GMC Yukon with Nav system that has 2-yr old software, i.e., the map info is out of date. But when I asked the GMC dealer about an update for the software I was told that no such thing was available - unless I wanted to pay $600+ for a "replacement part" map DVD. This seem ridiculous because all other consumer GPS nav systems offer updates either for free or for a nominal fee. Why is the automotive industry ignoring the consumer on this important issue?

Optional Information:
2005 GMC Denali V-8

Already Tried:
Went to dealer and got no satisfaction.