FBM orders from FBA listings and Amazon keeps blaming everyone else but themselves

I keep getting FBM orders from items that has only FBA listings.

1st time, they said "Dont use inventory upload feeds" - In 16+ years of selling on Amazon, I have never used feeds - not even once. I dont even know how to use feeds

2nd time, the blamed my 3rd party software. I asked my 3rd party software and they said its not possible. But I turn off the software just to test what Amazon was saying. Well...it happened agin

3rd time, Amazon says 'When the FBM order was placed, there was an FBM listing" . lol...really? In other words, now, there is NOTHING I can say to prove them wrong. They will continue and simply say "there was an FBM listing and now you deleted it".

What bunch of incompetent and lame customer service. I have never worked with a company that never ever takes the blame for anything that goes wrong. Amazon is a joke. Cant wait to blow out of this place.