Always check the business bank account as often as possible, ensure HMRC correspondence goes to Directors, open the post yourself, sometimes there’s a nasty surprise in there.What the fuck has your accountant been doing for 12 years not to ask you sooner?
Secondly what the fuck?
Nobody goes near my business or money without me looking at it first I don’t give a flying fuck who it is.
Get a lawyer.
Accountant in this instance should be threatened with Court Action but at the very least sacked, what a wanker not to advise about dividends that were not going into the OP’s account.