Rogue Amazon customer – rinse and repeat fraud

Hello fellow sellers. I am selling on Etsy and Amazon (FBM). Quite recently, a buyer emerged who started using the following tactic: she buys my products, uses them, then applies for a refund without returning the items, claiming high postage fees. She does this repeatedly – rinse and repeat.

Etsy was very kind and blocked her from placing further orders from my shop. Then she found my products on Amazon and started buying there. Same tactic: she buys, uses the product, and then requests a full refund claiming “she bought by mistake.” Amazon pre-approved her refund, and she wasn’t required to return the items. Nice.

How can I stop this scammer from abusing me on Amazon? I already reported her, but Amazon responded that they don’t see any violations on her part. If she orders again, I’ll cancel her order, but I know that will hurt my account health. At the same time, I can’t keep accepting this kind of fraudulent behavior from someone who openly exploits Amazon’s system. It seems Amazon doesn’t care because I’m the one paying for it.

What would you do in my situation? I’m sure others have dealt with customers like this. Can you actually fight repeat offenders? Can you block them? I’m moving to FBA soon, and from what I understand, I won’t be able to cancel her orders anymore, right?