This guy seems to really have a beef. A long time ago I was contacted by another seller who had also had issues with this seller.  He seems to really have a vendetta now. He tried to buy on an old account and even though I had him blocked on all his accounts he bought again recently.

The background to this is in this thread;

What would you do? - The eBay Community

At the time I was tempted to send him a message through the sale that I cancelled to say somthing along the lines of "We cancelled the sale as we identified the contact details matched details from an account we had previously blocked and as this is a violation of eBay's policies we have cancelled this sale. We will not be reporting this to eBay at this stage, but any further attempts to damage our account will lead to action being taken". I thought this might send a warning as I am sure he does not want any eBay investigations. But I decided not to send this in the end. So, perhaps he does not know why I cancelled the sale, and as such is trying other ways to sabotage our account. 

Does anyone have any advice on how to protect ourselves with this regarding the 2 returned sales? I am going to see if I can find any links between these two accounts and the 'rival seller'. Any help and advice gratefully received.