Non paying bidders!!

Does anyone have any advice on how to prevent non paying bidders?  In the last month I have had 5 non paying bidders despite having blocked anyone with a non paying report against them.  Is there any way I can tighten my exclusion criteria so that I can stop these nuisance ebayers from bidding on my items?   Since ebay have stopped sellers from leaving negative feedback, the number of non payers have just increased as we can't do anything about it.  The non payment reports seem to amount to nothing.