Basically we had a group of bullies in our office that were made redundant for the good of the company and they have done nothing but write lies on Glassdoor. How can a platform have reliable reviews if they aren't verified? You could literally write anything on there and get away with it. They don't care that this hurts smaller businesses as 5 or 10 reviews will make a huge impact on your ratings. It's ok of you run a company with 500 people as the good would probably outweigh the few bad eggs.
Very frustrating but doesn't seem to be anything that you can do to resolve it if someone is out to defame your company.