Whether it's Nintendo or a UK-local entity they sub-contract (it's a bit unclear - either way the address is store.nintendo.co.uk and Nintendo-branded), the policies could use some work.
It's infuriating to see big corporations act like bullies behind their lawyers, and equally satisfying to see good people stand up to them.
The best thing Nintendo could do - and their senior managers have a window of opportunity here now - would be to deliver a huge apology to yourself personally, along with a promise to review their entire delivery system processes.
But, at this point, I do recommend engaging counsel. As I understand it, truth is not a defense against slander under UK law.
Edit: I meant "libel", not "slander". Also, I was wrong about truth not being a defense. It's just that you need to prove the claims.
The onus is on the person who said the thing to prove it is true ("guilty until proven innocent," since it's a civil rather than criminal offence), but as long as he has documentation/emails it's all good.
Indeed, I would be astonished if they sued him for this, it would not end well for them.
Disclaimer: not a lawyer, but an election agent.
(I just got a quote this morning for a what I thought would be simply "explain my property deeds", and it came out at £500...)
I really would not recommend getting involved with libel law on a pro-se basis.
It most certainly is. Defence #1, in fact.
Under US law, the burden of proof rests on the plaintiff.