How do I block a user from messaging me?

[geckosrock99]

This guy made an offer on one of my heavier items listed for sale. In his offer he told me he'd buy it for free shipping, but didn't add any extra money to cover the cost. Naturally I declined it and told him I always charge shipping. He got pretty angry, sent me a listing of a similar item he claimed to buy and is harassing me about how I won't be able to sell mine at all. I already added him to the block buyer/bidder list and I put the check mark on for blocked buyers being unable to message me, but he just sent another message. I'm getting annoyed as I have done everything I can think of and I can't figure out how to contact eBay about it to report the user. He is ticked off as he wrongly assumed I charge outrageous amounts for shipping. I only add the weight and shipping service provided and let eBay do its thing. I just want him to leave me alone.