On the web, you have lost control of the conversations that can impact on you, anyone can say virtually anything they like, and unfortunately because it is “out there” it can gain traction, take on some credibility.
If you cannot control it, you need to be aware and find a way to participate in the conversation as a means to present the facts, alternative views, or a different perspective as a means to debunk the nonsense that can accrue in the absence of facts.
To do this, you need to be an active participant on the web in the forums and communities that talk about your product or service.
In the old days, (and even today) if someone prints lies in a magazine, you could sue, gain a retraction, an apology, some compensation, but on the web, you can do little to force a retraction, the best you can do is enter the debate and point out the nonsense.
Are the skills and aptitudes to effectively debate on line present in your organisation? At the very least, they will be cheaper than lawyers who will be totally ineffective, so look at the cost just as insurance if you cannot see the value in communicating directly with those interested in your product.