http://community.secondlife.com/t5/Merchants/Customers-receiving-Marketplace-items-that-I-am-not-paid-for/m-p/1237931/highlight/false#M12123
I just posted on a similar though not identicle issue. I have also filed a ticket because I am now concerned how many are getting my textures quite unwittingly for free!
Compared to some merchants my takings are small fry, I feel even more sorry for anyone selling expensive items!