Negating a negative is a genuine thing and, of course, two negatives make a positive! At JudgeService, if you choose to publish your testimonials, we publish all of them (unlike some other review providers that cherry pick and only show the good ones to fudge the results).
But these negative reviews actually help aid conversions too. At least, they do if they are handled correctly. 30% of consumers assume online reviews are fake if there are no negative reviews!