Dear Garmin,
Your users have spoken with a unified voice, and I think it merits a response from you to address it.
It's only fair that your users know your intentions to either stay the course with Bing or move back to Google maps, or make it a user defined choice. This will allow us to decide whether to stay with you... or move to a competitor. Saying nothing will probably drive more to the latter.
Please acknowledge your users comments.
Chris I.