wonder how returned items from costumers are not checked by amazon upon receiving and before refunding the buyers.

i requested to return unfulfilled items to my store and after checking them i found that some on them was used and returned one was broken and parts are missing from it and one received the box but different item was inside the whole inside package was changed how can i request amazon to check the items after being returned to them.

and i got a direct complain from costumers that they received used products.