Google Map Problems
We've made custom plugins to extend our GeoCoder plugin before that allow customers to manually adjust the position of the map pin (and thereby update the stored latitude and longitude) but that only fixes it for a CMSB website, really what the client needs to do is update Google Maps directly. The reason is that they're going to have people searching for them through the internet and mobile version of Google Maps as well, and it's kind of like the phone book at this point so it's important to keep it accurate.
Here's a link on updating Google Maps: https://support.google.com/maps/answer/162873?hl=en
I've made about 4 updates to Google Maps in the last year, fixing incorrect driving directions or addresses for locations I commonly go. It can take a couple weeks for it to update, but they will update it.
Hope that helps!