True, Skyline. Write to the directors at the company's registered office, which may be that of some accountants' firm whose address is used for the purpose, and not an address from which the company trades, but that doesn't matter. It is still the only official address of the company and appears on their correspondence.
A company is a separate legal personality from its shareholders, directors, and employees. Therefore a breach of contract by the company can only result in an action against the company, and only if the company has enough to pay the damages will the claimant get them all. Directors sometimes volunteer to pay the company's debts, but they then list whatever they pay as a loan by the directors to the company and hope to get it back from the company in due course. They may do this simply to stop the company being forced into liquidation, because they think, given time, it will prosper. They can't be forced to do so. And sometimes directors are obliged by a bank, that lends money to it, to personally guarantee the loan to the company so, if the company defaults, the bank can claim the money from the directors. Otherwise the directors are not liable in the ordinary course of trade.