It's possible to get billed for things not exposed in the UI. ~10 years ago, I had one of these. A Glacier upload chunk was stuck in a staging area for over a month. I couldn't complete or cancel the upload, or remove the chunk. Support was able to, and they refunded the money without much hassle. But I did have to reach out to support (as a <$100 per month customer) to ask. Glacier was new, so I chalk it up to it being a new product, not anything greedy or malicious.