As Sandy said, cancel the sale using the reason the buyer didn't pay. That will give the buyer a strike on their account. If they get 2 or more strikes in a rolling year, then they find they can't buy from sellers who have blocks in place. Do you have blocks in place to prevent serial pests from buying?
Further to what the other 2 said about feedback, it is actually a violation of rules to leave a false positive comment for a buyer. If you did, and the buyer reported you, you will get sanctioned. Do it too many times and you'll never be able to sell again.
If you're not sure how to set blocks, go here . Scroll to the bottom and tick to block buyers who caused 2 cancellations of unpaid purchases in 12 months. Also tick to block buyers whose primary delivery address is in a location I don't post to.
Turn on, don't allow blocked buyers to contact me (note, if you block a buyer after they've had a transaction with you, like your current non payer, they can still contact you for 60 days, then they are blocked).
Turn on, apply above settings to active and future listings. Then click submit.
Also at the top of that page is the blocked buyer list. Add that buyer's username there. I think you can add 2,000 names.
Also under the buyer requirements section, there is a link for manage buyer requirements activity log. It's good to look in there occasionally, maybe once a month, and that will show you how many members have been blocked from buying from you. It won't show you who they are, but should say the reason why they have been blocked.
