I assume youre dealing with a Limited Company?
You need to find out, in writing, the status of the Company - whether its in Administration, being Liquidated or just being wound up (or none of these).
If it's Administration you will possibly get your money. If in Liquidation it's unlikely you'll get anything. If it's being wound up then you should get paid.
I dont think going to the Small Claims Court at present will do any good (as it will cost you more money) until youre sure of the status.
Also, I think you need to actually speak to this accountant to make sure this isnt just a ploy to delay or not pay you.
Of course, the moral is not to let credit arrangements go this far adrift (but you know that now). Always state your terms and if the customer isnt paying then you dont do any more work until you get paid.