So long as your reply is short, balanced and factual then a reply is better than not replying. If nothing else it's extending the courtesy that we'd all want ex

So long as your reply is short, balanced and factual then a reply is better than not replying. If nothing else it's extending the courtesy that we'd all want extended to us if we were making a complaint (saying, sorry, no, you've made a mistake), but also you're kidding yourself if you think these things go away when you ignore them. Reality is that it's more likely that they'll escalate. In terms of could you charge for it, no of course not, sadly that's not how any of this works. You can throw out this sort of threat with little or no comeback.