buyer says he never received item

[chambly59]

getting frustrated with buyer who says he never received $20.00 item. one month after shipping item via regular   canada post buyer says he did not receive item. I replied to buyer saying that he should receive it shortly this goes on for weeks where's my item where's my item. Finally i tell the buyer that i will replace his item free of charge. so i sent it registered mail the item was delivered to his door. The next day i get a message from the buyer saying to me ¨ did you have time to ship my item are you kidding me or what should i report this buyer to ebay this guy could be doing this all day!!! with $20.00 items 

[mario909]

If you are a regular seller on Ebay one of your move is to put the ID buyer on your ''Blocked list''. So he couldn't bid on your item anymore. And you had probably made the observation that you couldn't put a negative feedback on him either. So this Ebayer probably make this processus to steal without possibility to subscribe any negative feedback against him.