GPS Review explains how to correct an error in a map provided by GPS unit or online mapping service — a process greatly simplified by the fact that, at least in North America, there are essentially only two mapping providers (Navteq and Tele Atlas), which you contact directly. It’s easy to tell which provider to contact, since each GPS manufacturer or website uses just one of them. But don’t expect a speedy resolution: “The total process can take anywhere from several months to multiple years. I don’t mean for this to discourage you from reporting the issue — by all means report it as it only takes a few minutes to submit. But don’t expect that the issue will be fixed within a few weeks.”