Don't forget to open an unpaid item dispute, so you get your fees back. As it's been 10 days, you can open one up straight away (you normally have to wait 4 days). Then, no sooner than exactly 4 days to the second after you open it, you can go back and close it. That will automatically refund your fees and the buyer will get a strike on their account. If they get more than 2 in a rolling 12 month period, they will be restricted in who they can buy from.

Also set up buyer requirement blocks so you block buyers with 2 or more strikes in a 12 month period. It weeds out the serial pests.