Andor I think you're in the best position to prove is they're real or not. Buy an iFixIt battery that's guaranteed to be real, and compare it to the ones from Amazon. Check the labels, weigh them, etc.
Additionally, even if the ones you're buying are real, how can you be sure they're not used?
The reality is that none of us can reasonably prove that your batteries are fake or used. However, if you're having horrible luck with the cheap batteries from Amazon, why are you not at least open to the possibility that you need to buy them somewhere else and maybe the ones you're buying are fake, used, or maybe just old? Why argue so that you can keep buying batteries that don't work? None of us care of you want to buy bad batteries. In fact, I've got some bad batteries I can sell you if you want some more.