Since OP thinks it could be a scammer doing it, perhaps just check the referral header and display a big banner stating that listing on Maps is not you and to n

Since OP thinks it could be a scammer doing it, perhaps just check the referral header and display a big banner stating that listing on Maps is not you and to not contact them and list real services/competitors? Will stop people from contacting them in favour of real businesses if that's the case.