UNEXPECTED FNSKU nonsense

I have been doing Amazon FBA for about 1 year. Some products have FNSKU barcodes and I send these products regularly. I also do double checks when we prepare these products. There are a large number of missing units in my last 2 shipments. When I make a claim for these, I get NONSENSE answers. The same answers are given without listening to me!

I sent about 900 units in one shipment. First, 900 units were added to the inventory. But then I saw that 117 and 60 units were missing. When I asked about these, I got the Unexpected FNSKU answer. This was impossible because I was sure that I double checked them all.

In my other shipment, about 208 units were missing. Where are these products going? I got the Unexpected FNSKU statement again. Again, no evidence!

I could not find a support team that listened to me and tried to solve my problem. They did not even provide any evidence for this! I guess Amazon does not care about seller support as much as customer support!