I've found it almost impossible to remove bad reviews on Google. We've had several drive-by 1 star reviews from people in different countries that have zero relation to our business.
It's even hard to get 5 * reviews removed. They aren't allowed for consumer finance co's in Canada but we still couldn't get them removed.
Did you use the report functionality or did you go through support? If the review has no relation to your business it’s a clear violation of the review policies and you can report it. For us nothing happened after reporting such reviews and only after contacting support they got removed.