Would like to block a buyer

[butterflycupcake14]

I had a buyer bid on two listings. When the 2nd one ended, I waited a day before emailing her, which was Christmas. Even after emailing her, then sending an invoice, she never communicated with me, so I opened an unpaid case, which she took her time to pay. Now that she has received her orders, I'd like to block her, but will she still be able to leave feedback afterwards? I don't trust her and want to make sure she cannot bid/buy from me again. Please advise.