pteam

In my 2011 GL350 the navigation has been acting up. I input a destination an even though I am on a main road it says I am miles off the mapped route. The past time I made it to the road that my destination was on and the gps continued to say I was off route. I had to send my father on an emergency trip and it looked to be doing it again and I'm super nervous that he will not be able to get there because it said once again that we were off route and never seems to recalculate. Any one ever have this issue or know what the problem is ?