If you could sue via class action lawsuit, which you cannot, would equate to what- .83c per person? Waste of time. You are under the 'terms of service' and have agreed to those terms by simply using this site.
So, let's get to the meat/potatoes- here. You CAN respond to a negative, but do it as if though other buyers will see how you reacted, if you react personally, this will not bode well for you for future sales. 2nd, you can try to sue the individual for defamation etc. but you would have to do it in THEIR jurisdiction.
Best to just let it get buried in future positive feedback, as if a buyer checks and you're in the high 90's with minimal issues, that won't stop most from purchasing.
You can also report the negative
You can also 'call' to try to get it removed if it violated something. If it just an 'opinion' of their experience, seldom will it be removed.
ps- looking at the verbiage used, these will be deemed as 'nothing wrong' with the verbiage, therefore it will not be removed. Boots are always tight, that buyer is just not helpful. The other 'you couldn't locate' was a problem for the buyer. If it was left accidently and meant for another, you can ask them to revise their feedback.
