We run an eCommerce platform, have a variety of clients using it, they have a number of customers. At least once a week we get an accusation either from a client or an end-user of some outlandish nefarious behaviour, usually due to some complete lack of understanding of the nature of technology.
Way back when, we responded, tried to help, tried to explain, but it tends to be the case that if someone has made their mind up, they've made their mind up, and anything you say can and will be used against you - confirmation bias is a harsh mistress.
The best response is usually no response, I'm afraid to say. It's a drain on your time, they won't be any the wiser unless you're prepared to sink serious time into educating a stranger, and more often than not responding results in escalation, and people doing stupid things like involving lawyers and law enforcement.
Case in point: About six years ago, we had an older guy phone us up frothing about how we'd hacked his wife's computer and she'd accidentally bought something from one of our clients. We explained that it would be hard to accidentally enter your address and credit card details, and that if they didn't want the order they should contact the merchant, not the web developer (they clicked our "ecommerce by" link in the footer of the client site - we don't do that any more!). We thought that was that. A week later we got a stern phone call from an ombudsman who wanted to know why we were ignoring the distance selling rules and taking advantage of old people... and they didn't understand that we weren't a merchant, didn't place an order on their behalf, either - so months of time were wasted, and we narrowly avoided ending up in court over a non-issue.
Anyway. When you have a conversation with an idiot, nobody watching can tell which one of you is the idiot.