Carton delivered to facility with two units-I received a defect that the two units were not present...I did not ship an empty carton

This is not the first time nor will it be the last that I have been told items were missing from a carton we shipped in, but this one is the most frustrating. This is pertaining to case ID 16959893331 if Amazon is reading.

Case FBA18MJ7F953U000001 was delivered to the facility. I received a defect that two items were missing from the carton. Ironically enough there were only two items in the carton. It was a manufacturer case pack of two. The items were labeled with my own 30 up labels so they do not comingle. I received a defect on my account for 2 items missing from the carton, plus I am out the two items. There is no way the carton could have been checked in when there were only two items in the carton. I believe the carton was only ever delivered to the facility. When I reached out to customer service I was told it is accurate and the two items were missing from the carton. What other options do I have to combat this? I had even submitted the invoice to show I was the owner of the goods that were sent in. I did NOT send in an empty carton to Amazon. I even asked them to verify the weight and the dimensions of the box to see that I did NOT send an empty carton to the facility. This happens more often than it should, but this time with it being two items sent in and two missing is ridiculous. I have been doing FBA for nearly a decade. Any guidance on next steps?