Untrue negative comments on RateMyProfessor website I pay close attention to how my rating scores/comments are like on the RateMyProfessor website. Very rarely I reported inappropriate comments (which violated site guidelines) for removals, and the average score has been decent (4.8). 

Since last week, after I reported a comment (with improper language which violates the site guidelines), very suspiciously the same student (who is angry about their bad grade) has been trying to (even until now) leave 10+ intentionally untrue, deceiving comments with low scores. 

My average has now been brought down to below 4.0. I've been frustrated because this severely compromised all true comments left by previous students. I reported this to the site and am still waiting for a response. Any suggestions?
As the comments suggest, just ignore it. You will always have disgruntled students even if you do a great job. Some will blame you for their own shortcomings. 

But the best "defense" against such negative comments is the positive comments from those who think you served them well. If those appear also, then a reader can easily judge it for what it is. 

If you want to "sabotage" such things, just point other students to the site, without comment. You don't need to "defend" yourself when your other students naturally do so themselves.