I need to bring mine into the dealership for the same reason, except we've experienced this with the windows closed and no a/c on...total silence in the cabin. We carefully enunciate an address, it pauses and then says "98.7 FM "and changes the radio. At other times we clearly speak a known address and it comes back with 4 choices to choose from and all of them are all over the map - some as far as 60 miles away from our destination. We have rarely been able to get the voice activation to do the right thing, but when manually inputting addresses, etc, it works fine. Anyone know about a TSB for this?