Experience Buying from Seller at AliExpress that We Need To Learn

How was your shopping experience on AliExpress?
Sometimes good sometimes bad. One thing I learned recently though : never spend more than $20 on an item sold on Aliexpress. Also make sure the sellers rating is above 98%.
I’ve bought several items that worth around $30 and up…and for whatever reason it’s always met with problems. Shipment suddenly canceled without warning or very slow shipping time (and you have to ask for refund manually because it’s not automatic and sellers probably hope we don’t notice).
The latest problem I had was with a seller called blgmUm. I didn’t check the store rating before I made my purchase so that was on me.
I bought a bedding set worth around $100. After I bought the item, seller told me that item is out of stock. So naturally I canceled the order.
Here’s the thing with Aliexpress which I find very strange—sellers must approve your cancelation request, even if the reason is perfectly valid (I. E. out of stock item)
4 days went by, and I received a message from the seller : the bedding set I want came in stock and they shipped the item—without asking if I still wanted the item!
I already bought another bedding set from a different Seller in those 4 days, so I didn’t need the item anymore.
I complained and asked them for a refund. Here’s the dialog :