Not Accounting for sale of all goods

on 23 May 2014 we delivered 505 units to be auctioned to them . they accounted for the sale of 332 units only. despite our numerous calls & emails to them they insisted that all our goods were sold & paid for. during November 2015 they sent us an invoice for the sale of goods that was not ours. Auction Pro requested that we call to collect the cash. we are honest people & informed them that this was not our goods & that they have listed our sellers account number on the invoice in error. we then emailed Auction Pro & copied the owner Trevor requesting that they check if they did not make the same mistake when they sold our goods in may 2014. to date they have failed to respond. we will like all sellers that take goods for sale to Auction Pro to be careful.