Moz: Yes, Competitors Can Edit Your Listing on Google My Business. “I decided to write this article in response to a recent article that was published over at CBSDFW. The article was one of many stories about how spammers update legitimate information on Google as a way to send more leads somewhere else. This might shock some readers, but it was old news to me since spam of this nature on Google Maps has been a problem for almost a decade.”
This echoes the problems I had managing a Google My Business listing for years, including one memorable weekend when spammers/pranksters/what have you had managed to mark the business closed when it wasn’t. If you’ve got a Google My Business listing you have to keep a close eye on it. Don’t rely on Google to alert you to anything.